I did a thorough checkup of my GRiSO today after it was rollerized last week. I noticed something odd inside the right side valve cover. [You must be registered and logged in to see this image.]
It's not very visible on the photo, but the powdercoat-like finish (not sure if its paint or something else) on the inside of the cover has partially dissolved. The light 'dirt' on the rubber gasket are small flakes of the aluminum paint. For certain these will end up in the oil, which I doubt is healthy for the engine. I cleaned all the loose bits, but even a fingernail is enough to cause more loose paint.
My technical knowledge isn't good enough to determine how bad this is. But if this is harmful to the engine, it might be wise for others too to check the inside of their valve covers.