Hey people, I need some help. I was cleaning my D70s today, and now when I look through the viewfinder, there's a mysterious line from the center straight down. When I look through the viewfinder when it's off, it's not there, and in my pictures, it's not there, but if i'm looking through the viewfinder and I turn the camera on, I can see the line appear. Any clues what this is? Something I left behind after cleaning the camera? Thanks.