Food delivery controversy

I am a late-night food streamer. On a rainy night, at two in the morning, the delivery driver knocked on my door. I stream myself eating late at night, which is surprisingly popular online. I was in the middle of a live stream, excitedly showing off to my audience. "Just drop it at the door," I called out. Ten minutes later, a notification popped up on my phone. "I'm gone now. You can grab it." Just as I was about to open the door, I froze. How did he know I hadn't stepped outside yet?