Bro what is the exact thing that you spotted inside the lens?
Related to coating on the internal elements, dust spots, weird reflections etc?
The only qualm I have with the 28mm is that the lens elements that look purportedly to be glued as a group to the barrel was quite crude... I can see glue marks or whatever they call it.. Haha, but the 50mm F/1.8G seems like the same as well to me and it doesn't affect anything although I wish that they did it better on a pro lens. it could just be me though..
Btw, any butties know which element is the one coated with the Nano crystal on all N nikkor lenses?