1) Better ventilation 2) Let the moss dry out thoroughly between mistings. The snake can handle it. 3) Consider keeping the cage dry, and then soaking or putting the snake into a humidity box a few times a week. I do this with my pythons, and their skin stays nice and supple, but the cages remain dry and easier to keep clean that way. Mandarins aren't pythons, I know, but both require some humidity and so the idea might work.