Are you sure it was real? Was this a shop on a cruise ship? I assume most people wearing Rolexes are wearing fakes. Mainly because one of my friends has a really good fake and me and him have started to question (to ourselves) some of the people we know that own them.
He was gift a fake when he was in Australia seeing a family member. He made a comment about his in-laws watch saying something along the lines that he must be rich. So he took him to his stash of fake Rolex’s and gave him one.
We posted it on Reddit and people couldn’t tell if it was fake or not. Honestly the best way is to takeoff the case back and take a picture of the movement.