Have you noticed that sometimes your cats can walk into room unseen and appear at your side as if by magic? Popsie does that a lot when I'm in the kitchen. It's like poof, he's suddenly there.
Last night I was upstairs saying goodnight to DH and Popsie was up there also. Well, I came down stairs and then heard a ruckus. I though Popsie was getting in to trouble in the bathroom so I was like "Popsie, what are you doing?" He meowed at me and I repeated the question. Then he came walking up from behind me!!! I never saw him come downstairs. Cats are sneaky.