Fair or unfair?

I was talking with a girl on MSN. We were getting along great, having quick banter as you do. Then, all of a sudden she said I was beginning to annoy her. The reason? Apparantly, I was taking the mickey out of myself too much! Now, I like to rip on girls I like a bit as well as myself. I always have done. I didn't realise some girls may not like it when I make jokes at my own expense. It's just my way of making someone feel at ease with me. I was shocked at her reaction because I was ripping on myself. What did I do wrong?