I knew it was a thing cats did - Maisie used to do it to Mum regularly before we got Spike and after Spike and I moved out - but hell, I live in four rooms total and they're mostly not full of clutter. I just couldn't see where the hell a cat would FIT that I hadn't already searched. Even a small one.

it's some sort of dimensional shift, I'm guessing. She fell asleep and forgot to phase back into our plane of existence.