Not to take sides or feed an argument, but if you'll look real close at the pictures the OP has posted, you'll see that what we're thinking is marbelling/mottling, is NOT at the new growth areas. I has appeared at the edges of the original scute from when the tort was just out of the egg. So if it has just now happened, it is probably not marbling, as marbling would appear at the new part of the new growth, not at the very old, original part.
