Found: note on my car

I parked on a side street near Alewife the other day and took the red line into work. When I came back at the end of the day this note was on my car.

I was a bit taken aback. This was a public street with no limitations on parking. I wasn't parked in front of anyone's driveway or sidewalk. I wish the note had been a bit more explanatory about what the problem was.