I feel like I might post here too often, but there is no one else in my circle that keeps snakes... Could this maybe be sent marking? Now that it is winter, and I have the heating on, the humidity is lower in my home. So my two snakes haven't had perfect sheds. So, I made shed boxes/hides out of tupperware containers with damp paper towel inside. Both hides have yellow brown stains on the paper towels by the entrance (and new ones appear when I change out the paper towels). There are no solid pieces, so it isn't poop. Is this a sent mark?