Celie did more of a half bow, half curtsey, trying to ignore the fact that this man spoke to his reflection. She didn't think that reflections could speak, let alone hold a conversation or even have separate personalities, but there were so many things in the world that she didn't know - it wouldn't be too surprising if they did.
"I go by Celie. Nice to meet you, Zeran." As for his earlier accusations - she wasn't crazy. She didn't think she was crazy. It was entirely possible for someone to be crazy and think it was normal, but she was pretty certain that she wasn't one of them. And this man didn't seem crazy, to her, either. He had manners, for one, and he was incredibly polite, something Celie didn't consider going hand in hand with 'crazy'. And even if he was, she should still try and be nice. People liked nice.