I've got a neighbor whose cat is veritable feline Houdini... he gets out every so often. And usually, it's to come over to my green house and steal carrots. (yeah, don't ask. he doesn't eat them. doesn't take them home. We have no idea what he does with them.)
Don't ask questions. just embrace it. (I've gotten to catsit Sykes on a few occasions now. the old man is a blast.)