Something in the sky or something on the lens?

A few nights ago I was taking some photographs of the clear star filled Arizona sky. Outshooting just north of the Mexico border in Nogales, Arizona.  I was photographing to the south over Mexico but was getting way too much light pollution from the big city in Sonora. Nogales, Mexico it's quite a large city so the lower portions of my shots had visibly less stars in them. This was not the type of shot I was going for so I decided to shoot towards the northwest. I started to get some nice shots and actually found a really cool tree to use as my foreground. I snapped a couple long exposures and was quite happy with the outcome. Since I was on vacation for the Christmas holiday, I did not plan to be doing star photography during the cold Nogales nights. I decided I had a great shot and I was going to head in for the night. As I was collecting my gear I noticed a really cool shot towards the northeast. There is a large house on top of the mountain completely decorated with Christmas lights. I thought that would be a great shot with all the beautiful stars in the background. So I set up all my gear and made a few exposures. I came away with a couple cool shots but nothing that really grabbed my attention. I decided to take a couple more shots reframing my composition and see if I got anything interesting. Well, interesting is just what I got. The frames that I shot came away with a very strange anomaly in the upper left-hand corner of the photograph. 

As you can see, there is a strange light pattern and interesting star shape. What is it? I have no idea. Is it something strange in the sky? Is it lens flare? Is it a reflection caused by the camera? I don't know. I tried to re-create the shots multiple times but I could not. What do you think?

Full image in the camera

Full image in the camera

Zoomed in image in camera

Zoomed in image in camera