I'll keep an eye out for scale rot, though I haven't seen any signs of it, just this slight discolouration. I actually have been using damp moss in the hide on her warm end, and that's helped her with humidity. I'm hoping after her shed this time this issue will fade.. Nothing happens if I wipe it or soak her, after she dries off there's no change. Otherwise she seems very healthy, good appetite etc, this had just been something I've been worrying about.