The first thing I'd be wanting to ask the owner is if he's like this all the time with strangers. Was he like this when your puppy wasn't around?

He could be missing his mom very much and scared of his temporary environment. How much was he socialized to deal with strange places? Most people have no clue just how important socialization is. Chis need it as much as any other dog, and I never get any Chis in class because their owners think they are small enough to control, unlike big dogs who can't simply be picked up and carried away.Very damaging thinking process - many Chis end up in shelters because of this idea.