Advice? Did I handle this correctly?

So I work alone nights (10pm-6am) at a gas station. A few nights ago I had a young gentleman who came in who was deaf. He was buying some snacks, managed to get the cigarettes he wanted and he was trying to find a way to communicate with me that he needed to get some gas. So I grabbed a pad of paper and wrote down what he needed and he wrote down what it was so we could confirm it. Well little miss Karen behind him had to tell me that I was being rude to him.