I just wanted to edit a comment of mine that was shown as "3 min ago". When I hit the button to commit the edit, I was told that editing is only possible for 5 minutes. OK, so I took too long to edit? But when I hit cancel, it showed only "4 min ago". I tried again, and only after having no success again and cancelling again, I got "5 min ago". Is there something wrong about the 5 minute time limit versus the displayed age of comment? Even taking rounding issues into consideration, the "4 min ago" after (forced) cancelling seems to indicate that something is wrong (or unexpectedly offset).
From your description is sounds like the time on your computer is a few minutes wrong.