In a situation like this, and this isn't to say you handled it poorly just how I would have handled it, I think it would have been good to educate the person who was questioning. Education is the key to making open carry more accepted by people. When he asked if it was real or a bb gun I (after a light chuckle) would have said that it was a firearm. That would have likely led to the other citizen, hopefully, asking more questions.
On a whole you did well and I'm glad that you had such a good experience. Also glad that the LEO was accepting of the situation and didn't try some crap like "oh, look, you alarmed a citizen; come with me please." Most don't seem to care, but it's not impossible for something like that to happen.