Someone I don't know has smiled at me and said hello twice. I do not know her name, but I know we have at least two classes together. Usually in this kind of situation I am not entirely sure they are talking to me and I am afraid of saying hello to someone who isn't talking to me because they couldn't care less about me and so they'll be annoyed, but somehow it was rather clear with her. Anyway, how would you interpret this? Is this meant to be some kind of invitation for further interaction? We haven't even had a conversation though. Why would she want to interact with me?