Bicycle detail

I was biking to pick up some baby gear from my friend. My friend and her kids were coming down the steps to see me, so I took my baby out his bicycle seat on the front of the bicycle, left the bicycle parked in the driveway, and went up the steps to greet them. They invited me in, and 15 minutes later, my friend's 3-year-old daughter said she had seen someone take my bicycle out of the driveway a few minutes earlier. We went outside and confirmed it was gone.