I don't think it's so much that people are offended by being mistaken as a piper, Todd, just that some kilties (myself included) despair that others think the kilt is only suitable for pipers to wear. In North America, we sometimes have a bad habit of trivializing culture, so when someone sees a person in a kilt, they assume that person must be a piper. Why else would they wear a kilt? People just need to be educated that it is the modern national dress of Scotland and not just a uniform.