In the registered user section there's a label: Seen.
It is showing incorrect information. When I visited my own profile page I got the information:
Seen: 18 mins ago.
According to what criteria is this info shown?
Not sure where it gets the information for that section, but the time error has a 99% of being a result of using caching. Wouldn't consider a bug, and isn't all that important anyways; unless of course you're stalking someone.
Edit: After reading your other question I agree that online/offline could be useful, but the specific time of last seen not so much.