Like Sunnie and Craig said, I agree that to me they just look like marks from rubbing against something also. The ones on her back are probably from the hide you removed. The one under her chin looks like substrate staining to me. Although, I’ve usually seen it with those who use cypress mulch. I know you mention you use coconut husk. I haven’t really seen staining from that before, but I would imagine it’s possible.
Have you tried wiping it gently off, like Craig mentioned?