Sorry for the late reply TMC, I just read your post.
I don't really understand your what you asking for? Are you seeking documentary proof?
Bubbles in lenses aren't really a bad thing but the contrary, the presence of bubbles show that the glass was cooled correctly and in the early days of photography, people would look out for bubbles as an indication of good glass. However, it is no longer acceptable in our day and age to have these imperfections.
My buying experience with these High end Nikon AFS zoom lenses hasn't been all that great (flocking flakes, dust, bubbles, grinding swirls) - I thought that paying a premium for expensive glass means that there would be less imperfections but I found the opposite to be true. It seems there are less imperfections in cheaper glass.
If you going to get the 28-70 - I suggest you check the one you are purchasing out thoroughly.
Ohyabashi Camera in Umeda was pretty good about allowing me to check out their lenses before purchase (the large stores like Yodobashi don't allow this), plus Ohyabashi was the only store I bought from that doesn't fill out the warranty card like the rest do. And they are willing to discount and eager to match the prices in Tokyo.
