Years ago, during a college trip to London, I began carrying my wallet in my front pocket to ward off pickpockets. My strategy paid off when a little kid in a Yorkshire in a tent erected for some local festival, filled with little pence slot machines. I'll never forget the look on the kid's face when I turned after feeling the little hand pop into rear pocket and pop out, and then turning to see a mystified look--"where's the wallet?". It made me a lifelong carrier of wallets in the wrong pocket.
At the Subway sandwich, therefore, I had to negotiate traffic a bit to get things rearranged after the phone false alarm (or false vibration).
I finished work at a reasonable time, and went to catch the bus to the train. But I found that my keys were not in my pocket. I hiked across the way to Subway sandwiches, and the guys behind the counter looked in "lost and found". But they said that their manager would have locked day shift keys up in her office.
My wife graciously agreed to come pick me up, so I could try to find if my keys had fallen from my pockets in my office. I crawled and crannied about, but they were not to be found. I used an office key to lock up.
When we got home, I'd left the key at home. It's funny--all my fantasies about sandwich shop clumsiness or setting the keys down at work, and they were at home. I did not miss them, because I did not have a car to drive.