Not using the official Bethesda textures saves me like 50gigs I can use for mods, but you get the odd thing like this that looks really bad. Its probably included in some pack of textures but I just found the vanilla miniscule one and improved it, also fixed the seams on both diffuse and specular.
As ever with Fallout 4, its a terrible idea to use loose textures so stick this in another ba2.