Is my BP starting a shed?

[Malum Argenteum]

Don't ask me how they avoid this in the wild...I just know that some snakes, including BPs, have been known to get thermal burns in captivity from poorly regulated heat sources.

I suspect the heavier-bodied snakes (like BPs) may have more trouble with this because it takes longer for the heat to penetrate their heavier body, & by the time they really feel it, their outer skin layers are damaged.

That last part is probably a clue as to why wild conditions don't (or do they? do we have reliable data on wild snakes?) lead to thermal burns. Wild conditions are going to be more uniform over moderate sized areas. If it is 100F in some area that area is probably pretty big and the air there is hot too, so the the snake (a) isn't coming into the area with a cold body, and (b) is going to heat both relatively quickly and (c) do so through radiant, convective and conductive heat. A wild snake is also likely to have a very wide choice of thermal gradient options (all the options in hundreds of square meters, at least).

Compare this to captive conditions where the cool side is pretty cool, and the snake is often supposed to warm itself mostly only through conductive heat (all the while loosing heat on its back side to the cooler air). This (that is, the relative heat gain/loss, as well as the the time needed to change body temp) is going to be more of a problem with a snake that has a lower surface to mass ratio like a BP. Add to this the fact that a captive snake is usually only given the choice between one cool spot and one warm spot (maybe a couple in the better enclosures, but 1000x less choice than in the wild), and it is no surprise that snakes have issues.