"W: GPG error: http://mozilla.debian.net squeeze-backports Release: The following signatures were invalid: KEYEXPIRED 1352888501" error

[Phillip Pi]

Dear Sir or Madam:

Your key expired today. I did not see this problem before yesterday on 
my almost a year old Debian stable box:

# apt-get update
Hit http://security.debian.org squeeze/updates Release.gpg
Ign http://security.debian.org/ squeeze/updates/contrib Translation-en
Ign http://security.debian.org/ squeeze/updates/contrib Translation-en_US
Ign http://security.debian.org/ squeeze/updates/main Translation-en
Ign http://security.debian.org/ squeeze/updates/main Translation-en_US
Ign http://security.debian.org/ squeeze/updates/non-free Translation-en
Ign http://security.debian.org/ squeeze/updates/non-free Translation-en_US
Hit http://security.debian.org squeeze/updates Release
Hit http://backports.debian.org squeeze-backports Release.gpg
Ign http://backports.debian.org/debian-backports/ squeeze-backports/main 
Translation-en
Ign http://backports.debian.org/debian-backports/ squeeze-backports/main 
Translation-en_US
Hit http://security.debian.org squeeze/updates/main Sources
Hit http://security.debian.org squeeze/updates/contrib Sources
Hit http://security.debian.org squeeze/updates/non-free Sources
Hit http://security.debian.org squeeze/updates/main amd64 Packages
Hit http://security.debian.org squeeze/updates/contrib amd64 Packages
Hit http://security.debian.org squeeze/updates/non-free amd64 Packages
Hit http://backports.debian.org squeeze-backports Release
Hit http://ftp.us.debian.org squeeze Release.gpg
Ign http://ftp.us.debian.org/debian/ squeeze/contrib Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze/contrib Translation-en_US
Hit http://backports.debian.org squeeze-backports/main amd64 
Packages/DiffIndex
Hit http://backports.debian.org squeeze-backports/main amd64 Packages
Ign http://ftp.us.debian.org/debian/ squeeze/main Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze/main Translation-en_US
Ign http://ftp.us.debian.org/debian/ squeeze/non-free Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze/non-free Translation-en_US
Hit http://ftp.us.debian.org squeeze-proposed-updates Release.gpg
Hit http://ftp.us.debian.org/debian/ squeeze-proposed-updates/contrib 
Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze-proposed-updates/contrib 
Translation-en_US
Hit http://ftp.us.debian.org/debian/ squeeze-proposed-updates/main 
Translation-en
Get:1 http://mozilla.debian.net squeeze-backports Release.gpg [828 B]
Ign http://mozilla.debian.net/ squeeze-backports/iceweasel-release 
Translation-en
Ign http://mozilla.debian.net/ squeeze-backports/iceweasel-release 
Translation-en_US
Hit http://deb-multimedia.org stable Release.gpg
Ign http://deb-multimedia.org/ stable/main Translation-en
Ign http://deb-multimedia.org/ stable/main Translation-en_US
Ign http://deb-multimedia.org/ stable/non-free Translation-en
Ign http://deb-multimedia.org/ stable/non-free Translation-en_US
Ign http://ftp.us.debian.org/debian/ squeeze-proposed-updates/main 
Translation-en_US
Hit http://ftp.us.debian.org/debian/ squeeze-proposed-updates/non-free 
Translation-en
Ign http://ftp.us.debian.org/debian/ squeeze-proposed-updates/non-free 
Translation-en_US
Hit http://ftp.us.debian.org squeeze Release
Hit http://ftp.us.debian.org squeeze-proposed-updates Release
Hit http://mozilla.debian.net squeeze-backports Release
Hit http://deb-multimedia.org stable Release
Ign http://mozilla.debian.net squeeze-backports Release
Hit http://ftp.us.debian.org squeeze/main Sources
Hit http://ftp.us.debian.org squeeze/contrib Sources
Hit http://ftp.us.debian.org squeeze/non-free Sources
Hit http://ftp.us.debian.org squeeze/main amd64 Packages
Hit http://ftp.us.debian.org squeeze/contrib amd64 Packages
Hit http://ftp.us.debian.org squeeze/non-free amd64 Packages
Hit http://ftp.us.debian.org squeeze-proposed-updates/main Sources/DiffIndex
Hit http://ftp.us.debian.org squeeze-proposed-updates/contrib 
Sources/DiffIndex
Hit http://ftp.us.debian.org squeeze-proposed-updates/non-free 
Sources/DiffIndex
Hit http://ftp.us.debian.org squeeze-proposed-updates/main amd64 
Packages/DiffIndex
Hit http://ftp.us.debian.org squeeze-proposed-updates/contrib amd64 
Packages/DiffIndex
Ign http://mozilla.debian.net squeeze-backports/iceweasel-release amd64 
Packages/DiffIndex
Hit http://deb-multimedia.org stable/main amd64 Packages/DiffIndex
Hit http://ftp.us.debian.org squeeze-proposed-updates/non-free amd64 
Packages/DiffIndex
Ign http://mozilla.debian.net squeeze-backports/iceweasel-release amd64 
Packages
Hit http://deb-multimedia.org stable/non-free amd64 Packages/DiffIndex
Hit http://mozilla.debian.net squeeze-backports/iceweasel-release amd64 
Packages
Fetched 828 B in 1s (764 B/s)
Reading package lists... Done
W: GPG error: http://mozilla.debian.net squeeze-backports Release: The 
following signatures were invalid: KEYEXPIRED 1352888501

I looked at http://mozilla.debian.net/ to see if I need to update my key 
or something:
# apt-get install 
http://mozilla.debian.net/pkg-mozilla-archive-keyring_1.0_all.deb
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package http://mozilla.debian.net
E: Couldn't find any package by regex 'http://mozilla.debian.net'

# gpg --check-sigs --fingerprint --keyring 
/etc/apt/trusted.gpg.d/pkg-mozilla-archive-keyring.gpg --keyring 
/usr/share/keyrings/debian-keyring.gpg pkg-mozilla-maintainers
gpg: directory `/root/.gnupg' created
gpg: new configuration file `/root/.gnupg/gpg.conf' created
gpg: WARNING: options in `/root/.gnupg/gpg.conf' are not yet active 
during this run
gpg: keyring `/root/.gnupg/pubring.gpg' created
gpg: keyblock resource `/usr/share/keyrings/debian-keyring.gpg': file 
open error
gpg: /root/.gnupg/trustdb.gpg: trustdb created
pub   4096R/06C4AE2A 2010-11-20 [expired: 2012-11-14]
       Key fingerprint = 85F0 6FBC 75E0 67C3 F305  C3C9 85A3 D265 06C4 AE2A
uid                  Debian Mozilla team APT archive 
<pkg-mozilla-maintainers at lists.alioth.debian.org>
sig!3        06C4AE2A 2011-11-15  Debian Mozilla team APT archive 
<pkg-mozilla-maintainers at lists.alioth.debian.org>

2 signatures not checked due to missing keys

Thank you in advance. :)

Sincerely yours,
Phillip Pi