I've never shot fresh HIE, and I've also never had a roll that showed any age. Some expired in 1999. My impression is, the people who stocked up on the stuff (and for whatever reason never got around to shooting it) were highly aware of its sensitivities, and stored it properly.
I have exactly one roll left, and it's in one of those lead-lined airport film bags, in the freezer. If you are going to hang onto your stock, might want to look into something like that.