I'm wondering if the color change was mostly because of the snake being in the sun and having "older" skin that is due to shed soon. I noticed that on our darker colored BP yesterday. When she was in the sun she was lighter like that, especially her head scales. Inside she looks pretty normal, if not a bit darker because her skin is probably getting old. Except under a bright light you can still totally see her "old" lighter skin at certain angles. I have seen this before on her too, shortly before she enters shed mode.