Yea, some boas tend to do that in loose substrate. Some just prefer their hides. Just be carefull! If you have a
UTH right on the bottom of the tank, the snake can burn itself. If you do have a
UTH right on the underside of your enclosure, put some spacers under it to give about 1/4 inch between the cage and heat source. If your
UTH is flexwatt though, you should be fine. It's such a low voltage power source that it probably will never pose a threat to your critter.