I was just shining a flashlight at the undersurface of the front element of my 17-55 - if you look VERY carefully (or under bright sunlight), you can see a fine speckled appearance, or powdery appearance. Is this normal? Is this just the lens coating?
note that it's not on all lens surfaces. It appears most obviously only on the back surface of the front element of that lens. It's possible other lenses may or may not exhibit it.