I inform them that I have a permit, and that I'm carrying. At the two random checkpoints, I did this while I had both hands in plain sight on the steering wheel.
While changing a tire in the emergency lane of I-40, I let the officer know that I had a permit, but that I'd put the firearm in a lock box in the car.
When being interviewed in my home by an officer responding to a call, I informed him, then kept my my hands in sight during the interview.
I've had positive reactions every time. Three of the four times, I was thanked for handling the situation the way I did. The fourth (the home visit), after the interview, he asked me what I was carrying and we had a brief discussion about guns.
Maybe people that live in other states or communities have more problems. But here in NC, the police are generally supportive of CCH permits.