Did you go on vacation between the time when it was 3 hours and 23 hours? There's a weird issue (that I feel is a bug, but I've seen rationalized as a trade-off between the 1 day minimum vacation time and game time) that adds 24 hours to your game clocks as soon as you go on vacation. If you come off of vacation before the 24 hours you retain the extra time on your game clock.
Can't explain the jump from 23 to 25 though -- are you sure that you saw it right?
This afternoon I had three hours left to play in a game that I had moved in this morning (or late last night), but it is three days per move.
Just now I had 23 hours remaining in a game, but two minutes later had 25 hours remaining.
What's going on?