Are you sure he didn't leave a little gift for you somewhere?
If not - it is a bit odd that he hasn't pooed, but if you haven't changed his food or anything - I wouldn't worry too much. Since it's late - I'd probably just wait till morning - then see what happens. Make sure in the a.m. he drinks alot of water. He should go in the a.m. - if not, you could give some canned pumpkin to get things moving..
