Quote Originally Posted by SmartWombat
Does it only happen in portrait, and not in landscape shots?
Or when angling the camera up, but not shooting straight & level?
That would be a strong indicator of focal plane shutter problems.
Orientation of the camera shouldn't make any visible difference in how the shutter is performing unless it has already failed or is about to, like in right now. Even with a polarizer the banding shouldn't be lessened if it is a shutter sync/binding or follow problem.

I talked to a RF fan today who scowled at the mention of ACROS 100 and muttered unkind things about the film and pressure plates in many modern and vintage cameras mechanical cameras. From that source it makes me believe there is engineering at play to take into consideration keeping tension on the film to make it flat as you find in a motor wound camera but not in a manual advance. That would produce another problem however.

If a second roll of film consistently show this, then the final test is to see if the camera syncs with a flash at the appropriate setting. If there's a 'follow' problem, 'The second curtain isn't traveling at the same speed as the first' it will be highlighted when using flash.
Sometimes it is bad enough that you can see the outline if not the surface detail of the shutter itself from reflected light. If that is the case though, usually you wouldn't be getting any even closely usable exposures.

Let us know what other info you discover. I hope it is not your shutter, warranty or not.