[Gmail-Users] Google's Security Certificate Expired????

I usually read my Gmail via POP access. When I logged on this afternoon
the following screen (see URL below) popped up in Mozilla Thunderbird.

http://angrykeyboarder.com/images/off/expired.png

I accepted the expired certificate but I can't help but wonder what the
heck is going on. I can't imagine Google would let something like this
lapse.

To make sure I wasn't crazy I asked my roommate to check her email
(Gmail) and she got the same result.

Scott