Just because you're paranoid, doesn't mean they aren't out to get you...
Sorry, but if I saw a plane circling overhead emitting clouds of white smoke, it would freak me out too, and I'd call the cops. Nothing "Chicken Little" about it.
I'd like to think I would recognize an aerobatic plane by sight, but there is no reason one of these couldn't be stolen and used for terrorism the same as a cropduster.