Well, I've been OCing for nearly a year now and today was my first verbal acknowledgement/encounter. I stopped by Meijer in Okemos on the way home from work to pick up a few things. At the self check line the clerk came up to me to key in his code, then as he walked away I asked him if he had a wine tote bag. He came back with one, handed it to me, and turned away. He then turned back again and approached me a third time and said, "Excuse me, what does your shirt say?" I turned to face him and showed him. I was wearing this white polo with grey dress slacks.
"Opencarry dot org. Oh." he said, smiling. "My niece and her husband just got their concealed licenses, and they let me shoot their snub-nosed 38. That was the first time I shot a handgun." Yeah, those small revolvers are not the easiest guns to shoot, I say. Real short sight radius. He keeps talking about shooting, and I was kinda wishing we were somewhere else so I could unholster mine as a talking point, but I didn't figure coonfingering a loaded Five-seveN in Meijer was a good idea. But someone came up to him with a question and he left.
I've talked to people in stores and restaurants all over the area before while OCing many times, but either they've not noticed or ignored it. Walked past LEOs without a word. This was the first acknowledgement I've ever had. Which is good.