It depends on whether or not your ambient RH also changes. If you have a leak and the ambient RH drops at night and your media can't keep up then your humidor RH will also drop. If the ambient RH rises back up during the day then the RH in the humidor will rise as well.
FWIW, pretty much anything you use as a humidor will "leak" to some extent. The trick is to get the "leak" to be as small as possible.