Anytime you make a change to their enclosure, it can take them several days to get used to it. Just switching out one hide for a new one can make it seem like they are rejecting the new hide...but they're just taking their time checking it out. Their world moves at a much, much slower pace than ours. For all we know, he may believe some other creature has moved into his little cave and it will take him a few days to convince himself that he's still alone in there.