So, I found two rolls of Elitechrome in a random box of my photo stuff the other day. Both have been sitting around at room temperature (~75 degrees) for a year or two and are a few years expired. One was exposed and the other was not.
For kicks, I shot the unexposed roll and sent them both out for processing. When I got them back, the roll sat exposed for a year was heavily magenta fogged while the other roll was (more or less) perfect.
It is conceivable (but unlikely) that these rolls were stored under different conditions before I received them -- a friend gave them to me around when they expired. Since I've received them, they been together, both stored in their canisters.
Is this a real thing or is it a fluke? If so, what causes it?