I doubt those belly spots are mites. Belly isn't the favorite place for mites to hang out. From what I've seen, mites are usually easiest to notice around the eyes. It is a bit unusual though since motleys are supposed to have pure white bellies. Maybe little bits of substrate dust get caught in her scales? I haven't used anything but aspen and newspaper for substrate, so not sure if that could happen.
She is very pretty. My favorite pics was the one where she was all coiled up imitating a ball python. So cute! She even had her head tucked under!