There was an issue some years ago with white chips, from some Florida cruise line, that would oxidize over time. I don't know if this is what's happening with yours. You mention that the affected chips were stored in a red box. Maybe some chemical is being released over time from them. I would suggest storing chips in a white box, or perhaps wrapping the chips in an additional baggie or some such, made of archival-quality material of course, so that the chips are not directly exposed to the walls of the storage box.