I was so confused. LOL! I think people who are trying to raise humidity move the water dish under their heat lamp. If you are making a humid hide, I think that it would make sense to put it over the mat, but I could be wrong.
Yep I'm agreeing with everyone about it being a possible stuck shed and eye cap. I use coco husk, and moss in my glass enclosures. I have moss in both the hot and cool hides and water dish in the middle. I also mist the crud out of the enclosures every few days to keep humidity up. I live in a dry climate and its hard to keep humidity where I want it. I do have a tub so I can "soak" my snakes but don't use it much. I throw a towel in the bottom, and just barely cover it with water except 1 corner so they can rest their heads on it. Neither of mine use their water bowls for anything except to drink and then throw their substrate in lol. I've never had a "perfect" shed but as long as everything comes off I call it a successful shed. Just stay calm and try some of the suggestions out and see what works for you. More than likely next time he sheds it will come off completely. Good luck.