Rogue Zombies!!

Yes. This happens a lot to me, although only if I have been logged out for a while. One human and one pet.

I've noticed it happening every few hours. I don't mind at all.

This has happened to me too, only one human and one pet, it happens once every couple of house and normally when the cemeteries are not done rejuvenating. Not that I mind at all, the more treats the better! :)

When I open the app, and I hit "tap" to go into the game from the loading screen, I listen carefully, if you listen you will hear a zombie moan, that means that there are zombies roaming in your town. Pretty sure people knew that though lol.

It appears to be part of the game since the Halloween update, whether you build the cemetery or not.
Everyday I get either a zombie dog or cat and a zombie man or woman suddenly appear from nowhere.