bug or feature?

I'm playing in a daily tournament and my opponent had 1 hour left when he went on vacation. a few hours later he stopped being on vacation and he now has 22 hours left without moving still. I'm quite new to chess. com and chess in general also. Is this a feature of daily chess? can I also do this?

Using vacation time will always use up a minimum of 1 day (an attempt to reduce the number of people that go on vacation just to delay a game they are losing).  If you come back from vacation before 24 hours have gone by, however, the unused portion of the day will be returned to you as real time in your games.

Thanks for the reply. I guess that's what happened then. It added 21 hours of remaining vacation time on.