If you found one adult mite, you can pretty well bet there will be more. You need to treat the snake cage with something like Provent-A-Mite for at least 2 months until you are sure the mites are gone. Otherwise, in a few week to a month, you start seeing more mites. Remember, mites arent confined to the cage alone, they can travel far in the course of a night but if you only have one snake, then i would bet, they would stay fairly close to 'dinner'.