Today while working in the Caf?, Lolly the Cat (one of my dreamies) came t the Caf? to order coffee. She doesn't live in my town. So I was like OMG!!!!! What does this mean when a non-villager comes to the caf??
It's a cute feature thrown in to make working at the caf? a little more challenging. If you were to just see your own villagers at the caf? everyday, you'd figure out their preferences quickly and the whole sidequest would be too easy.
It's just coincidence. I had the cafe before I ever went online and saw villagers I didn't know. It actually helps me. I can't remember my ten, but the visitor usually gives me enough information to get it right (you only need two out of three to know all three).