At first, Chekov wonders if he gave the wrong answer (but it was the only answer he could give). Then Kirk starts explaining and things click a little.

"Then they are hiding their advanced technology?"

Because he was brought in on a cart.

The question doesn't seem to bother him-- Kirk did act as if he'd been here longer. Somehow.

"I had just finished my shift on the bridge and was preparing for bed." He looks down at his bare feet, wiggling his toes. "That is why I have no shoes, Captain."