Are you by any chance viewing this in Lightroom or Photoshop? I had the same issue, but not when I looked at the same images in my windows Photo app. Apparently, it is a glitch with Adobe and they have worked on an fix because in my latest update it isn't showing any more. I suspect it is an issue with the algorithms used for lens correction data in those programs - so it's either their algorithm or the one supplied by Canon, but it seems to have been cleared up in my software.
cheers, TREVOR
The mark of good photographer is less what they hold in their hand, it's more what they hold in their head;
"All the variety, all the charm, all the beauty of life is made up of light and shadow", Leo Tolstoy;
"Skill in photography is acquired by practice and not by purchase" Percy W. Harris
