since the curing of a polymer is nothing else but the bulid up of a 3D-network this means that the chemical bonding of the monomers and especially of the of functional groups chance. This leads to a change of the probability density of the electrons within the polymers. This should finally lead to a changing signal of the NMR spectrum.
Curing of polymer leads to structural changes via cross linking. Thus 1H- NMR or 13C-NMR would certainly be different for a polymer before curing and after curing. As the chemical and electronic environment of protons or carbons changes the chemical shift and coupling constant also can change.