From time to time, shed does get stuck, even with good humidity. Some snakes just don't seem to know to start the shed peeling. I'm think this is what has happened to her. She is ready to shed, but just didn't rub and get it started.

If that is the case, when you pick her up the shed will be loose and crinkly under your hands. Gently pinch a bit of it up near her head, try and get it started for her. Generally they'll finish it on their own then.

Gale