You don't need to replace the NFC, but I'd replace the lower and upper if you're going to replace either of them. The Moto X depends on both antennas to meet their dual antenna MIMO spec. and it would be a waste of time to guess which one is borked up.
Before you replace the antennas though, I'd suggest opening it up and just removing / reseating the antennas first. It could be as simple as one of their connections being loose and introducing interference into the circuit.