Never handled High Speed Infrared, but I certainly understand films with distinctive smells. Kodachrome is definitely distinctive. I think High Contrast Copy is as well.
HIE uses a unique (and expensive) sensitizing dye to give it IR sensitivity. It's quite unstable over time, the film has lousy shelf life. So the decomposition of it may give off the distinctive odor you have noted.
It will be interesting to see if Ron knows (or is allowed to say) what the dye is. (It may be a trade secret.) I think Kodak had to synthesize it themselves.