If I set up a cube in solid mode and put the view inside it, I see what looks like a lot of banding:
If I up the contrast, it's a lot easier to see:
Is this normal limitations-of-8-bit, is it a blender problem, or could it be a graphics driver problem?
I realize it doesn't look like a lot of banding on the screenshot, but it's far more noticeable when panning around.
Edit in response to duplicate
This is not in rendered images (at least that I can tell), just in the viewport.