Did she have cat Food in her cart?
does your dog bark or get agressive on command? Noo I'm not saying that's what I would've done, not inside the store anyway, but I've wondered if service dogs are taught that.
That's probably all she eats...
This is definitly an example of being happy you are you... you have common sense and can easily reconize a cat women... she must have been so scared ....the nut..lol ..just imagine what your dog was thinking.. she was happy to be herself too...