To the OP -
Yeah, I know exactly what you're describing.
Lately, I've been expanding my circle of friends beyond 1 or 2 (plus family) so that I have several people that I trust and whose company I enjoy.
However, the number of people that really, REALLY know me are very few outside of my family. I mean, heck, I'll be transparent with my friends and communicate intimate facts about my situation or what I'm feeling but there is still another layer beneath that. Only the select few are granted access there.
When someone is granted access for the first time... they don't know what to think. "Where is the serious-minded, thoughtful, quiet, self-composed Wyst I used to know? And who is this ridiculously, animated, joker that now stands before me? WTF... did he just play a practical joke on me...? He must be drunk."
That's the real me though. (not the drunk part)