Chill out, man!
I can pretty much say for certain that she was not attempting to insult you, dude. Most of call each other by our user names anyway... just like most people call me 'Q', 'QBall', or 'QBall1970'. This is the very reason why they are called USER NAMES. It's not a sign of disrespect to use said name... after all, YOU chose that name to reflect your personality here on the Board.
If you don't want people to call you Mandy... or something similar... then I suggest you change your user name someway, somehow. Besides, it ain't the brightest of ideas to be giving people on the Internet your real name. Kinda dangerous that... especially with the issues of identity theft, etc.