It's still possible she could have mites even though you're not seeing them. They can get under the scales and irritate the BP. Do not use NIX though, I'd recommend PAM. You don't treat the snake, just the enclosure while she isn't in it. (Directions are provided with product.) Even if it isn't mites, treating the enclosure is a great preventative. That enclosure is beautiful, but a bit too big for her right now. She'll grow into it, but you may want to clutter it a bit more. (plants, newspaper, etc.) Though, that is up to you because obviously she is eating fine the way she is. I wouldn't take her to the vet just yet, considering she is eating fine, just keep an eye on her for changes in behavior. I can't think of anything but mites that would cause her to soak so frequently. It's obviously not a humidity problem considering the humidity is above normal. (Should be between 50-60% while not in shed, closer to 70% during shed cycle.) I'd lean towards mites. You can order Provent-A-Mite online, I'd strongly recommend it!