What kind of substrate are you using? Mites can be difficult to see, as they are only about the size of the period at the end of this sentence. They're most easily detected by putting in only white paper toweling for substrate and checking that for what looks like pepper grains after the snake has been on it for awhile.
Other than mites, if the snake does not appear to have any symptoms of a respiratory infection, such as gaping or wheezing, it may just be that he's still adjusting to his new environment. Some snakes go off their feed for awhile after moving, or in the winter, or for what may appear to us to be no good reason every once in awhile.
You might read through the "snake won't eat" or "BP won't eat" or other feeding issues threads for some ideas on how to tempt him to eat. I wish I had the time to post more, but I have an exam tomorrow and have to get back to studying . . .
Good luck!