What is this dark patch? Should I be concerned?

[Ax01]

When I took Kaa out of his tank to clean today, I noticed these pink patches around the upper half of his body. He's not acting out of the ordinary, just seems discolored near the head. I've taken a photo of the most obvious spot which is just behind his jaw. What is this? He ripped into a mouse pretty grotesquely last night (he didn't end up eating it, hence my taking him out today), so I thought maybe it's simply staining, but I couldn't wipe it off with a wet paper towel and it seems pretty pink.

yes, i would do that first. i've had some of BP's pop their feeders and get stained by blood and guts. they get stained where they throw their coils.6292

Edit: BTW u have a very good looking Albino.