My 7 year old 17-40L appears to have developed a moderate amount of de-centering, with the left side softer than the right from 17-24mm. I confirmed it isn't a focus issue by inverting the camera are re-shooting without refocusing. It's apparent at 100% and somewhat at 50% (when looking for it), but not really at web sizes. It's actually more obvious on the 50D APS-C than 6D FF, probably due to the finer pixel pitch pressing the resolution limits.
I realize this is a pretty common problem with this lens, and the borders and corners typically aren't stellar anyway, but it's bugging me and I'm considering having it repaired. Any experiences (good or bad) having this kind of optical alignment work done on UWA zooms? Given the relatively low price of this lens new, I'm tempted to sell it off (with disclosure) and trying a new one under warranty.