I've had this effect a couple of times. Once it happened the next day(!?) after I cheated a bit with time-stuff in the JS-console...I'm getting some very strange time jumps; occasionally the time skips ahead one hour or goes back by one, it's making attending the classes into a bit of an ordeal. I'm playing on version 0.3.13.4, the latest I believe.
All the other times no cheating whatsoever was involved.
It seems there is already a mitigation implemented. If you save the game and load it again it should be fixed.