Banding advice (seems pretty bad even at iso 100)

If someone wouldn't mind downloading this x3f and seeing if it compares to their DP2M files I would greatly appreciate it. I got the camera yesterday and yes the file is 2/3rds to a full stop under exposed, but once adjusted the obvious banding I have been seeing is really atrocious. Maybe I am overreacting or maybe my unit is malfunctioning.

The problem is most visible on the back of her head/hair.

http://i.imgur.com/b2yjO.jpg

http://www.filedropper.com/sdim0051

Thanks.