That is interesting. What format were did you shoot the photo in?
Jpeg, Tiff or raw?
When I looked at dpreview it lists as 8 bit mode in Tiff and 12 bit in raw mode.
It might make sense if they mean 8 bits per channel (RGB)
and 12 bits per channel. That would be great! But why do they keep it a secret if that were so? Be nice if Nikon shed some light on this subject.