N.C. Gen. Stat. § 45-18
Whenever before January 1, 1979, a trustee has been substituted in a deed of trust in the manner provided by G.S. 45-10 to 45-17, but the instrument executed by the holder and/or owners of all or a majority in amount of the indebtedness, notes, bonds, or other instruments secured by said deed of trust, has not been registered as provided by said sections until after the substitute trustee has exercised some or all of the powers conferred by said deed of trust upon the trustee therein, including the advertising of the property conveyed by said deed of trust for sale, the sale thereof, and the execution of a deed by such substituted trustee to the purchaser at such sale, all such acts of said substituted trustee shall be deemed valid and effective in the same manner and to the same extent as if said instrument substituting said trustee, had been registered prior to the performance by said substituted trustee of any one or more of said acts, or other acts authorized by such deed of trust.
N.C. Gen. Stat. § 45-18