I got home tonight exhausted and nauseous, certain a flu bug had set up camp in the supple lining of my stomach. Distracted and out of sorts, I shut the front door behind me and turned to insert my key into the lock.
But that's not what I'm supposed to do when I get home and shut the door behind me. That's what I'm supposed to do when I leave the office and shut the door behind me. I'm supposed to shut the door, and then lock it.
So I packed my aching joints and queasy organs back into the car and drove all the way back to work, only to find that I had, in fact, locked the door behind me.