There oughta be a law against....

There oughta be a law against people saying "What happened?" when they really mean: "I didn't hear what you said".
I approached a supermarket employee and asked: "Which aisle can I find the sandwich bags?"
She replied: "What happened?"
Well, nothing happened. Which aisle does this store display the sandwich bags?
She's not the first person I've encountered who uses "What Happened?" when they didn't hear you clearly.