Sounds like my guy, he did the same thing for me since then I always tip him a 5 and he really goes out of his way for my he'll come back twice in a day if i'm not home and asks when it's the best time to come, he's a great guy just trying to make a living, I think he knows whats in those little bags and always asks me how I'm doing.
I even called his manager and gave him an atatboy and he came back to thank ME, for what were paying 5 dollars won't kill us and its well worth it cause they could give us a hard time if they wanted to, so be nice and tip the guy