I haven't had any problems smoking in public as of late, I think the local community has seen me around enough to accept me and my pipe.
I do However remember being pulled over years ago when I was smoking my pipe. The officer came up to my window and asked me if there was a good reason why my car smelled of cannabis and kindly asked me to get out of the car in order to search it properly. I did as was directed and commented that "I'm sure there is a completely plausible reason for his smelling of cannabis" and he proceed to search my car. He put my pipe to the side and then questioned as to what was in the tobacco tin, I told him the mixture and its components then proceeded to give a small lecture as to the various strains of tobacco and their differing properties and tastes. Eventually he gave up his search (or grew tired of my monologue) and commented that he had found nothing amiss and no longer smelled cannabis and told me that I was allowed to return to my car. Upon parting, he did ask me why I said there was a good reason for the sent of cannabis and I simply stated that given his profession and upon seeing a young man with a pipe it was more than plausible that anyone of his fraternity would psychosomatically get a whiff cannabis. While this seemed to annoy him he did let me go on my way.