Yes. Under N.C. Gen. Stat. § 31-21.2, a codicil (amendment to a will) must be executed with the same formalities as a will:
The statute requires the execution to occur physically within the state. A North Carolina resident signing a codicil while temporarily in another state risks invalidity under NC law, even if valid where signed. NC courts apply lex loci actus (law of the place of execution) for formal validity, but the statute's territorial language ("in this State") creates ambiguity.
Include a notarized self-proving affidavit (N.C. Gen. Stat. § 31-11.6) to avoid witness testimony at probate.
When in doubt, sign in North Carolina. The cost of a plane ticket is trivial vs. a will contest.