I thought it was an ugly plastic doll with loads of hair but, as the person who called me one has never seen me, I'm guessing they have something else in mind!
Should I be worried?

I've no idea if you should be worried as I don't know where this took place but this is the definition of an internet troll.

http://en.wikipedia.org/wiki/Troll_%28Internet%29

A troll is someone who deliberately posts in order to wind up other forum members with the intention of causing outrage and/or upset for their own amusement.

Thank you. That's what they meant, although it was not justified.

I'd rather be the hairy doll!
Not guilty, for what it's worth