Happy to be free, Bert lounges in the afternoon sun.
It was my fault. He was probably lounging in there when Callie and I got back from our evening walk. He likely stayed very still when we came in so that Callie would not notice him. I didn't notice him, either, and I closed the door. At least he had some water in there. There was no sign of distress, no poops or any sign of digging. He just waited for the door to open and then, when it did, he ran out like a shot, and went directly to his kibble bowl. Poor thing.