I have an EF-S 10-22, and it is the single worst hot spotting lens I own, when used on my IR converted SL1 body, and yet is totally fine on my conventional SL1. For wide IR I use the SL-1 kit lens, the plastic cheapo EF-S 18-55 Mk II at 18mm. It is very good in IR, but just OK with conventional photography. The best IR lens in my kit, again a cheap model, is the 24mm EF-S pancake.
I'm not saying the 10-22 may have caused the odd coloring or hot spotting alone in your images; and I must agree with you that the light was probably just at an oddball angle at the time, or your angle to it was peculiar. Though it could also be a combo of both?



















