[Leica] Help: Banding in photo. What is it?

[kennybod at mac.com (Ken Frazier)]

Listers,

Here's one of the shots I didn't post because of the banding, about a third 
of the way up from the bottom of the image, just above the lowest set of 
power lines, running horizontally across the image.

Here's the link:

http://tinyurl.com/y9elzh

Any ideas what this is?  About 5 or six frames in this roll had the banding.

M3, Summicron-M 50/2.0 DR, BW400CN.

All help appreciated.

Ken