Well interestingly enough, crested geckos show their true colors at night. I have seen some dull brown cresteds turn flame red when you turn out the lights. Its really cool to watch. Tokays will often do the same thing, mine turning pale white with bright red spots on it. In any case, thats one possibility, a morph. The other one is infact shedding like you stated. In the tokays I have, shedding usually occurs on the entire body equally. However, if you have humidity problems or other shedding problems in general, shed may come off in parts. Shed on the head (haha rhymes) tends to be the last to go since it is usually the hardest for the gecko to get off with improper humidity. Basically my recomendation would be to raise humidity in the tank for the next few days (4 or so) and see how it goes. You can also attempt to peel it off yourself. If it is white, then it should easily come off since it has already seperated from his skin, thus it should not be hard to remove. A picture would help. Good luck.