Recent activity stream timestamps are wrong

I made the comment below at ~3:20pm EDT and then immediately took the two screenshots. On the article page, the comment is timestamped "Posted moments ago":



In the recent activity stream on my profile page, the comment is timestamped "6 hours ago":



(As I write this at ~3:30pm EDT the comment is now timestamped "7 hours ago".)

Comment URL: http://www.annarbor.com/sports/on-bot...

My profile page: http://www.annarbor.com/cgi-bin/mt/mt...