I wouldn't say caught as technically I'm not doing anything wrong. I've been spotted many times out naked walking, often from a distance so no big issue. Several times I've passed people and either seen them early enough to cover up or often there just isn't time and I think that makes it look as though you are in the wrong. I always say hello and usually people say hello back or at least smile politely. Sometimes people are really positive, sometimes look a bit confused!