Submissions get renewed sometimes and the time stamps are set to a newer time (this is to get it ranked high enough to hit the front page). All comments have a

Submissions get renewed sometimes and the time stamps are set to a newer time (this is to get it ranked high enough to hit the front page). All comments have a false (newer) time stamp for a while if they predate the renewed time stamp. After a few hours the original time is restored for the submission and comments. These usually come from the second chance pool (click lists at the bottom to get to the pool and some other lists).