D700 (high??)ISO banding
This type of artifact I have not seen on D700. What I did see at ISO 6400 and above is a grid-like pattern across the very dark areas of the image. It is not common enough, however, to bother me much, but I do look for it now, after I came across it a couple of times.
|Valley by the light of a blue moon by cjf2|
from Down in the Valley
|Lake Erie Stone Pier by yobbyt|
from Dock or Pier