What does it mean when a guy French Kisses you?

I went on my third date with a guy I really like and it's obvious he REALLY likes me. Yet, I want to take things slow and for our first two kisses we just had a peck on the lips. The third time we got pretty cozy sitting and talking together and when he kissed me he put his tongue in my mouth! I kissed for a little bit, then told him I'm not ready for tongue. I feel it's too intimate and for someone you REALLY REALLY want to be with. Should I be mad at him for trying? He just want ? I don't want him to think i'm easy.