Strange blue fringe on sides of my images

I was out shooting in snow with the temp around 20 degrees this morning. When I got home I noticed all of my photos had a strange blue fringe on the left and right sides when shot landscape. See the 50% crop of an unedited raw image. It's only visible when I'm zoomed out to 17mm. I tried a few test shots at home after the camera had warmed up and the problem seems to have disappeared.

I've never seen this before. Could it be caused by the cold temps? I'm thinking the edges of the sensor where it is attached to the camera might be cold.

I was using a Canon 5Dii and a Canon 17-40L lens. Most of the time I was stopped way down

EXIF:

Camera: Canon EOS 5D Mark II
Lens: EF17-40mm f/4L USMShot at 17 mm
Exposure: Auto exposure, Aperture-priority AE, 1.3 sec, f/22, ISO 100, Compensation: +1

Speculation:

1. sluggish shutter curtains from the cold

2. diffraction from the f/22 aperture

I believe this is shutter curtain drag caused by the cold. I've seen this a time or two when I shot film in 35mm on very cold days. Since the effect went away after the camera warmed up, I believe this to be the likely cause.

Diffraction, if was visible at all, would show as a lack of critical sharpness in fine detail and would affect the entire image, and would not likely present as a dark streak on the edges--at least not in my experience.

--P

I'm not sure what this is. I have used my 5d mkii outside for hours at a time at -5 degrees F and not gotten anything like this. Generally, at the beginning of the day I use the camera, then if it is cold, I put it in a plastic bag and keep it inside my backpack in the vehicle, and that insulates it so it doesn't constantly heat up and cool down during the day. I have had times when the camera was cold for 8 or 10 hours and I've never had anything like this. Could be the cold, though, I guess.