Guys, OP and me are not expecting gratitude or monetary rewards. Honestly, there're times when someone did me a simple favor like holding the door or offered to press the lift button. I don't feel gratitude at all. It's simply a social etiquette and I just say "thank you". At worst, it's lip service.
Oh now, recalling back. Mofo didn't say xiexie. That should be a subtle red flag. Please unlearn your "Chinese peasantry mindset" if you think otherwise. That's why I hang out with other races and nationalities when I was overseas.