Don't know, but I get anomalies every once in a while, like a picture where the lower 3rd of the image is just black, like the picture file didn't completely write to the SD card.
It's probably something like that and part of another file has been written into this picture file or something. Make sure you have a good quality SD card, but that doesn't always guarantee you won't have an issue like this.
Maybe someone else has some other ideas.