Hard to tell but it appears to just be pigment. Does it hurt her? Can you wipe it off? Is it under the scales? Is she hatchery stock? Oftentimes hatchery stock pop up with some odd pigments.
I zoomed and looked as best as I could and see nothing that screams "mites!". If you are worried you can coat her legs in Vaseline. It won't hurt. At this point I don't see anything to be concerned about.