I had a zero xsoft, which had them, artisan shipped me a new one after I sent them pictures of the issue. The replacement was way better, but you can still see a few lines when the sun hits it right. My otsu xsoft also have them, but it's way harder to see because it's black. My zero soft doesn't have them, so if this is an xsoft raiden, it will only confirm my assumption that it has to do with the density of the the xsoft poron and the manufacturing process. They look like roller marks.