Last night before bed, Kitty was staring at the heating grate as if he heard someone or something behind it.
This morning, about the time he usually pushes his dish around looking for breakfast, he was chasing something around the room. I eventually saw something run under the door to the bathroom.
I opened it enough so Kitty could get in. He came out with a mouse in his mouth. Then he put it down and it ran away, apparently under the clothes dryer, which he watched intently for the next few minutes.