Wow! Oz did that today too!
I went out the backdoor to bring my mom something, and the door didn't shut all the way so he followed me out. I put him up, took my mom her stuff, and turned around and there he was! So I figured the door STILL hadn't shut properly and took him back to it.
When I got around the house, the door was shut securely and no one was in the house to let him out. I'm like WTF???
We have
Blink Dogs!