I'm the opposite....I love being on stage, and am pretty extroverted. I get nerves, but do it anyway. So I don't really know what to say about it....however, it sounds like she understands why you declined??? So I don't think its rude. I recently declined being in a wedding because I just couldn't afford to travel to NM and the bridesmaids dresses were like $5000....so money kept me from doing it, and she totally understood. Its not like you just said NO I won't do it!! She understands why it makes you uncomfortable so....I don't think it was rude. Maybe you can help in another way? Like helping decorate the hall before the guests arrive?