An RI can be very subtle. The rescue I got didn't display any symptoms of an RI except one day I heard the slightest whistle come from him. I barely heard it. If I had not been right near him, I wouldn't have heard it. I took him to the vet, and sure enough he had an RI (vet tech heard him whistle). Keep an eye on her, but she may just be soaking getting ready for a shed.
It does seem like she's moving around a lot. I really do recommend you get her a smaller set up. It can be very cheap to do. People will sell used 10g tanks for very cheap (usually around $10). The whole set up should cost you less than $50. You can use butter tubs for your hides until she is large enough to move into a larger tank, and even then a 75 seems a bit too large, even for an adult female.