Probably, it just means your snake finds the temperature under the substrate on the cold side to be the most ideal.
But if that's not the case, it could be caused by not having enough proper hides, or maybe your temperatures are actually too hot. Are you using a thermometer with a probe to check the temps? Because if you're just using one of those stick on ones on the side of the tank they can be very inaccurate, and your hot side may be too hot for the snake.
But if you have enough hides, and the temps are fine, your snake probably just likes it there.