Stick the water bowl on the warm end of the enclosure, or stick in a moist hide like I did with my leopard geckos...
Making a moist hide
You can make it bigger or smaller depending on the size of your snake. If you find he's hanging out in there a lot, then the humidity is a problem.
Usually putting a water bowl on the warm end will raise this a little.
What kind of enclosure is he in? If it's a mesh cage, get it outta there asap.
1) Mesh cages ain't exactly great for keeping in the humidity in an air-conditioned room.
2) He could've damaged his eye on the mesh.
If it's a glass tank or a plastic tub, then you should be ok.
I use 12qt rubbermaid snaptoppers for my lil guys. They'll be good in there til they're about 18" long or so. I just drilled holes in the side for air, and they're doing good. Having a solid lid on the top helps keep the humidity up a lil too - as opposed to a mesh/screen lid on a glass tank.