As of last night, I now have the same problem as well. I think I'm going to try a method similar to what others have suggested here. I'm going to swing by autozone and pick up some touch up paint in whatever the darkest, non-metallic grey I can find is. Then I'm going to mix a very small amount of black in with some clear coat, and just keep adding coats til it matches. I'll let you know if I have any luck.
If that doesn't work... Screw it, I'll just go over it with generic black wheel paint and call it day. I'll probably be the only one who would ever notice anyway as long as the blacks are vagely close. My snow tires are going to go on these wheels anyway, so I doubt this will be the first time they take a beating.