Thumb's up to Aixa for standing up for her paying customers.
Put in an Open Records act with the local department, to see what the Computer Aided Dispatch is for the incident.
Go see their Captain or whoever is in charge of them and politely inform them about the incident. (No 'official action' may be forthcoming but Everybody hates to be negatively called to their boss' attention.)
Did Officer Tweedledee or Tweedledumb say that you had to inform then even when you're openly carrying?
Perhaps you should do just that, in a preemptive way. Call Dispatch (non-emergency number only please, you don't want to tie up emergency phones) and inform Dispatch that the Tweedles demanded that you to inform them that you were openly carrying. Ask them to relay to the Tweedles that you're going to be openly carrying at such and such location and that you don't want them to be surprised or anything. You might even have to call on an hourly basis or whenever you're going to someplace new.
Most of all, be polite (which means only laugh on the inside.)
I'm not sure about NC's laws, but are you required to carry your permit when openly carrying?
If not, consider going 'sterile', no permit and since you're walking and not driving you don't Really need that driver's license with you, do you? Go ahead and leave all that in the car unless Officer Friendly is offering to sell you alcohol, cash your check, or sell you an airline ticket.
Some officers love to play the power game.... until they realize that they're the ones being played.
It's perfectly okay to tell Officer Friendly to go pound sand, when they're stepping beyond their authority.