hmm then it might be too much if you're thinking of doing it all the time. what is the humidity in the hide with moss in it? if it's too high it might be an issue, cos then the snake can't choose to hide and be in in adequate temperature and not have the choice of humidity, if that makes sense...
i cover 3/4 the top with a damp towel and cover that with foil, but it needs to be rehydrated every few days, and i still mist daily and that keeps it in the mid 60% range... it's definitely tough to get it right with a screen top, takes much more maintenance!