That's horrible. I would be infuriated. 
I definitely take some sort of action, either towards the individual store or the corporation. I doubt they would even care, though. I notice when people leave complaints on Petco\Petsmart facebook pages, they simply answer a monotonous: "Hello, sorry you were not satisfied with our store. Please email us at soandso@email.com." It doesn't feel genuine, and who knows if any action was taken towards it. Did you question him on where he got that knowledge when he said that to you? I wonder what he would have answered. Sadly, most chain stores sell animals with little to no training whatsoever. I remember when I got my first hamster, a Petco associate sold her to us with a Crittertail kit, I remember it was around the evening when they were closing, so she probably wanted to get us out of there.
Sometimes I eavesdrop on conversations associates give to customers and laugh to myself.
PS: Your Chinese Hamster is GORGEOUS! I love her coloration! Where did you get her?