shedding question

[mrbass111]

my milk snakes belly scales look milky but the rest of her look normal except she has developed white flakes on her back. they dont come off and i did not know if that is normal prior to shedding?

[Auskan]

If you can post a pic, it might be more helpful than a description. I've never heard of something like this before, but its hard to know without seeing a picture.