Had a case right after the church shooting in Texas. My wife and I were walking thru the lobby of our church before the service and a guy just out of my peripheral vision grabbed my knife sheath that was "printing" beneath my shirt.
"Hey, the flap covering your pocket knife is open. You better snap it shut." He said rather firmly.
Caught off guard, I smiled and said thank you. We walked into the sanctuary and sat down about 10 rows from the back. The more I thought about it, the more I suspected he wasn't being hospitable but rather a little over aggressive in his suspicion that I might be a bad guy. Sure enough, when we got up to leave, he was three rows and directly behind me. We are regulars at the church and I'm fairly well known. I did not recognize him.
Moral of my tale is the first time was my learning experience. Even when not CC I now have increased awareness in crowds.
It may only take 2 seconds to disarm someone, so you better plan ahead and know what you are willing to do in those 2 seconds.