I have two juvenile garter snakes that I've had for a few months. They share an enclosure. I have a regulated heat pad on one side and I use heat lamps to bump up the air temperature. Substrate is aspen. They both have eaten well except lately, one of them is always hidden and does not come out when food is offered (previously, they would both show interest and poke their heads out when it was feeding time). Last week, I dug around and found him; when I showed him the worms, he ate.

I'm looking for advice on how to proceed. Is this normal behavior for this time of year? Should I dig around every time so he eats, or just let him be and when he's hungry he'll come out?