well, unfortunately its not new science. its quite basic.
the plastic and the wood just have a different absorption spectrum, so they get different amounts of energy input from the same light source. non-reflecting black absorbs the most, followed by reflecting black. Also, the plastic is so thin that it conducts heat very quickly and it has a low thermal capacity. Wood is quite a good thermal insulator, especially bark from trees, and has a decent thermal capacity. shape and airflow also play a role, hot air is lighter than cool air, depending on the shape it can be trapped underneath a hide or flow out.
its all fully understood i think.
its good that you have a temp gun and noticed the problem quickly and that the snake is fine. mistakes like that happen.