-
There's a reason they say don't eat food past the expired date. The labels are not kidding. The worse I got was nausea from expired chips I bought from the school cafeteria. I assumed they wouldn't sell kids expired food, but then again they sell stale bagels so it fits. And I thought tomato soup always looks like blood?
-
For some kinds of food, it can be a "just in case" thing to protect them from lawsuits. Seriously, hermetics are edible for decades, but the expiration date says just a few years. Dunno about your case. It could be the chips (I'm assuming you're not talking about fries, which the brits are known to call chips), but I wouldn't entirely rule out the possibility that it was caused by something else. If a bag of chips needed more than half a year to get past its expiration date, I really doubt one or two weeks more or less would make much of a difference.
Or maybe I've just built up an immunity to that sort of stuff :p.
Over here, we use "best before" instead of "expiration date", which I generally interpret as "edible after this date, but might not taste as awesome as it's supposed to".