It was just immediately obvious. The closest thing I can come to explaining it is that the way you introduced yourself was... childish? That's not really the right word, but I really can't come up with a better one. Maybe I mean something like overly eager? It was just immediately obvious you are different. Your mannerisms, facial expression, tone, I don't know, were off. I can't really explain it, but since it is usually accurate, I trust my intuition.