How odd and possibly creepy is this?

About a half an hour ago, there was a light knock on the front door. Since there is an operative doorbell and I wasn’t expecting anyone, the knock was ignored. Typically, it’s person dropping off a flyer, and they lightly knock to alert the owner.

I just opened the door, and sure enough, there was a lawn service flyer stuck in the door. No big deal. When I glanced down though, there was an intact light bulb on the stoop.

The first thought was that someone might have taken the porch light apart in order to provide a darkened environment for a break-in, but the light is untouched and in working order.

So why in the world would a person walk up to a front porch and put a light bulb there? It isn’t like someone tossed it from the street or sidewalk. The porch is about 20 yards from the road. It is made of a pebbled concrete surface. The bulb is glass. Are criminal shenanigans at work in our neighborhood?