It's also possible he had tunnel vision. There's a guy that I see almost everyday at the dog park and we've talked guns a number of times before. But just last week, I come down and he goes, "Hey! You're packin'!" (in a that's cool tone of voice). It's amazing what people fail to notice.
Either way though, it's good. You're not in the guy's face about it (Hey! Look at me I'm so cool because I've got a cool tool!") and he didn't notice...or he saw it for what it was and didn't care. Win-win.