Historical plates any cop problems ?

Other than wanting to check out the car, I've been pulled over three times for using year of manufacture license plates here in NC. Twice the officers did not know the law in which I informed them and showed them my real tag and registration. After going back to their car, calling it in, and being confirmed of the law on their radio, I was free to go. The third one the officer knew the law but just wanted to check my real tag. Was free to go immediately once I showed him my tag, he didn't even go back to run the #'s.
Usually when I sell North Carolina YOM tags I give a copy of the law to keep in the glove box just in case an officer does not know the law.