A while back, I was chatting with someone on gTalk who I had pissed off in a forum. The next time I tried to sign in, my password has changed. I had to do the reset.. when I signed back in, no signs of foreign IP access was there.

My best guess: malware on the forum OR they exploited a vuln on Gmail.com similar to how hotmail.com & yahoo.com used to be very very vulnerable..