Nice tank set up. And no you don't have to worry. I've had toads stay underground for a week or two and not come up.. or when they did come up I wasn't around. Just leave 5-10 crickets in the tank and they'll see them sooner or later, especially if they come out at night to hunt.

A deep ceramic dish filled with a few meal worms doesn't hurt either, as long as it's one-two inches deep they cannot climb out of it. Crickets either unless they get the nerve to jump which they often don't when confused and stuck in a dish like that.