Think about it...the AE fixture has a latch mounted on the door...and it sticks out a bit...so if the hinge is nicely seated...and would stay straight..and it's possible that it was slammed against the pole so hard a little pressure of the AE tab latch is holding onto the arm by its side....and it says that way by a little pressure...from the hinge and the tab....if you look very carefully the door isn't really against the arm straightly but slightly on the side...I believe I see its curved latch touching the side of the arm!
Beats me how it got like this, but I would have to agree with Jace's idea. Thats one good thing about the Model 13/25/327, they can't really lose their doors unless the latch is un-hooked. And Devote it couldn't of froze because it was 35 degrees Celsius of 95 Fahrenheit this day and had only been a month since the tornado.
i'll roll with jace's idea....sounds better than mine