Soft plastics on my nikon are an issue. I have noticed that they tend to deteriorate quickly on beach holidays. I suspect it is a combination of Sun, residues of solar cream on the hands and the salt in the air.
You mean the grip? Nikon rubber grips are notorious for falling apart. Which is part of why I sold all my digital Nikon gear when they were tone deaf and peddalled dSLRs and the dumbed down 1 system. Went with the m43. It's not an open standard but it's considerably more open than others.