I don't want to sound like a broken record, but what type of lighting are you using? There is a certain type, a compact florescent bulb that every pet shop sells but they create an uncomfortable environment at best and at worst, permanent blindness.
I'd like to see that ruled out.
The little turd is making a liar out of me. Today he came out of his hide by himself and ate his plate of food and was walking around most the day.
Don't judge one event as all is fine. Just keep doing the great job you're doing. With a little bump in temps, it's amazing how they come out of it. Is he leaving turds for you?