We have logic which asks is this time in the past? If so, we display "15 seconds ago", "3 days ago", or whatever. If not, we assume we're displaying the remaining window in which one is able to edit a recently-posted comment (issue tracker comments are editable for 15 minutes after being posted). In this context it makes sense to display "15 minutes left", "3 minutes left", etc.
What may have happened in this case is that your computer's time and the server's time are out of sync by three or four minutes. Perhaps we should only apply the "time left" logic for editing "windows", and display "just now" for all future events in other contexts (based on the assumption that future events will always be the result of small discrepancies in computers' times).
I'm against this approach, though, as it has the potential to mask discrepancies which are not insignificant (imagine the confusion caused if somehow all of one's commits were dated a year in the future). I think the optimal solution is to always represent times truthfully, accompanied by context-sensitive text. In other words, future events in feeds should be in the form "X minutes from now" rather than "X minutes left".
Closing as wontfix for the reason stated, although it would be nice to handle these edge cases gracefully.