Back to creepy encounters with staff in general:
Where I come from, it is not usual to tip in cafes, restaurants etc. People may leave some small change, but generally noone expects them to. Once, many years ago, me and my boyfriend (both in our early 20s) were having coffee at a cafe. After we are done, the waiter comes with our change, leaves it on the table and just hovers there over our heads instead of leaving so we can pick up the change and leave. After some akward seconds, he asks my boyfriend: "You won't leave me a tip?" !!!
My boyfriend said something along the lines of "even if I was, I am not leaving a tip now", we got our change and left. We never saw him at the cafe again, even though that place keeps the same waiters for years.