I found the same signage at the Charlotte-Morrocroft Harris Teeter today. I called the local store and the manager stated it became effective policy for ALL North Carolina stores Wednesday.
I contacted the HQ customer service and spoke with a nice rep named Julius. He said they received a few complaints from customers in NC who saw guns while shopping and were upset. He said the company takes customer complaints very seriously so they implemented a blanket-ban for all of NC.
Interestingly, Julius stated he also had a concealed carry permit and understood my frustration. He stated that if enough customers complained about the policy, HT would be inclined to reconsider.
1-800-432-6111, option 3 for customer service HQ.