I would be cautious. Most pet store's probably don't know what they are selling, but most people who sold to the pet store do. It's really hard for any morph to slip through the cracks.

Some snakes will loose color with a shed. It could be just a normal with a color issue. And, most will get their color back with-in a few sheds.

That's my professional opinion. Personally...... I would just on that like white on rice!! Even if it is just a normal, they come in handy every once in a while. If not, you are going to drive yourself crazy asking "why?"