Don’t worry, it’s quite normal for hogs to fall asleep in feeding boxes. I have had them before who stayed a couple of days. One even took a minimal amont of bedding in there the second night. It might be a bit inconvenient but it’s probably best to just leave them be. You were lucky that one went back to sleep again, it may have wandered off to try to find somewhere else.
I had one once who made a full elaborate nest right on top of a bowl which stilll had food in it! I had to get another box for feeding at the time.
It sounds as if the hog there has taken to the box you put him in so seems like a good outcome.