If things are going well with your snakes, you really shouldn't have to do anything to increase humidity. I never even give my corns humidity hides, but I also live in Texas which couldn't be more humid. And I'm really not sure what it is like there in Pennsylvania, but putting in the humid hide certainly won't hurt.
The snakes should normally have humidity around 40-50%. Of course, increasing that by around 10% will never hurt to do during shedding periods.
I honestly wouldn't be too concerned if I were you, and I don't think I'd pull out the saran wrap just yet. If you'd like to monitor humidity, go out and buy a gauge. Also make sure the heat is working properly. Otherwise, everything should go well.