If that's mucor (cat hair) you have problems. Mucor is incredibly sensitive to salt levels and usually only an issue on soft ripened cheese (like brie). If you have cat hair on a gouda, your salt is way, way off. We have some blue strains that do appear black and hairy, and are also somwwhat sensitive to salt, but it takes much more. The cure, in either case, is a rub with coarse salt.