Ok, so you need to put a hide on the warm side, too. And do you know that an unregulated UTH can, and will- I've seen it- reach 120-130F, which can burn your snake? So getting a thermometer and most likely a thermostat should be done ASAP. Until then, if you could get a ceramic tile and place it in the tank over the UTH, that will cut the heat down enough to keep the snake from getting burned. Then, many people don't feed or handle the snake for a week, to give it time to settle in. It might be a good idea especially for you to hold off feeding until you know your exact cool and warm side temps. Other people feed right away and have no problems, but a too cold or too hot temp could cause regurgitation, which you absolutely don't want to have happen. It won't hurt him at all to wait until you have the temps dialed in. So back to burrowing- snakes love to burrow- that's normal. If you don't have a hide right now, you can use any small box or toilet paper tube or something like that. They like those just as well.
Nanci