Perfectly normal
Your snake will turn blue and get darker during the shed phase. Then a couple of days before the actual shed takes place the snake will clear up and appear to have already shed. This confuses many new snake owners.
Do you have a humidity box for your ball? They usually have bad/partial sheds if the humidity is not high enough.
Make a humidity box by using a plastic container of some kind that will allow your snake to get in and out of. It should have a small enough hole to allow the humidity to be retained. Inside you will need some damp sphagnum moss. Not wet, but damp. If your snake needs it, he will use it, if not, he wont. But atleast it will be there.
A plastic butter tub can be used, and works pretty well. (depending on the size of your snake) If it is a pretty good sized ball, then a small sterilite container with a hole cut in the side should suffice.
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Good luck and Happy Herping
Brian