Ghost Photo?

I thought today I would do something a little different. I'm going to post a photo from one of my team's investigations. There's a strange anomaly in the photo, so I thought I'd get your opinion on the image. The shot is taken facing down a hallway and at the end of the hallway, there's something dark behind the door. The dark spot doesn't appear in any of our other photos of that doorway, or in our video.

Here's the original photo:

And here's a cropped and lightened version of the photo:

At first, we thought it was some sort of reflection from the camera, but we weren't able to recreate the affect in any other photos. The spot also resembles the face of a young girl, which is interesting because the property owner believes this area is haunted by a young girl. Also, when we watched the video of when this photo was taken, one of our investigators was calling the name of the little girl and asking her to come over. Of course, it's totally possible that there's a logical explanation for the photo, but it does make you wonder.

So what do you think is causing the anomaly in the photo?