Relax, burrowing and hiding in substrate is perfectly normal behavior. Some do it occasionally, some never do it, and some spend most of their time buried. If your snake is new, or its circumstances have changed (new home, new location in the room, new addition to tank, new AC, whatever) it may want to spend more time burrowing around. Also, if it's recently eaten or is getting ready to shed it's more likely to look for a secluded spot. Hope that's helpful.