What I mean is on the back of my new iPad, if I shine it in a light, I can see tiny vertical lines all over the iPad. It's only visible in direct sunlight, or in a well lighted area. Is this normal since it's brushed aluminum?
Yes, it does. It's the nature of brushed aluminium. However I think you're using the wrong side... turn it over and use the side with greasy finger marks all over it instead...