to the OP's point of people not realizing that others may be carrying a concealed weapon, i never really thought about it until i decided to carry myself. But i find myself saying to my wife a lot when someone does something stupid-"don't they realize i could shoot them?" not that i would, but that they are creating a situation that given the right circumstances could escalate to something very bad.
case in point, i live in PA and we were pulling into a parking lot of a Walmart much larger than the local one. As we were waiting for a car to pull out of a spot close to the doors(not a necessity to us as i usually park farther away). a lady and her teen son, he was driving cut us off and took the spot...as they pulled into the spot, forcing us to wait as they drove by, the lady flipped us off. my wife and i just laughed. We parked about 10 cars past them on the other said of the same row. as they got to the store front, both turned and flipped us off yet again. the son then wiped his eyes like he was crying. again, we both laughed. We ran into them again inside, and for the third time, received the friendly middle finger hello. After they walked away, i whispered to my wife, "they must not realize i have a gun".
with all the people going bat crazy for no reason any more, it would be a good idea for everybody to avoid trying to one up anyone else...after all they could just shoot them...even in "non-carry" states