The fellow at the service desk managed to find the expiration date, which was 1-9-19. Now, normally you would expect that this wouldn't be a problem -- it's really just a best by date, not a completely inedible by date. But something had gone badly wrong with these chips. He agreed to exchange them, so I went by the display rack.
All of the chips in front were from the same 1-9-19 lot. But there were some May-dated chips at the back of the rack. I grabbed those, brought them home, and they were pronounced good.
I let the fellow know that there were a *lot* of expired chips on the display. I am guessing that they will be gone soon...