Huh! I have 15 Red Tails, 3 Dumerils, and 1 Coastal and NONE of them soak at all. I would be concerned. Whenever a snake soaks it's usually for a reason. I'd up the humidity to 65-70% for a week and see if she stops.

Have you had a fecal done lately? Gone to the vet? Is she in a tank or a tub?

It is really unusual. All of my rtb's have large dishes and none of them ever soak, so (like I said) I'd start looking at the situation a little more closely.