Most animals you can kinda pull up the top layer of skin. If it doesn't immeditately snap back in place you may be experiencing some degree of dehydration. If when you pinch and the skin remains there...that's extreme dehydration. Of course with you're situation the skin pulling thing maybe a little stressful, so I would make sure you have a full bowl of water available. Keep it close to the hide they're in and keep an eye out. Make sure there is lots of cover so he doesn't feel like he has to give up security in order to reach the water. He may have already had a drink or two when you weren't looking so don't stress out too much, although I know how difficult that can be!