Folder.jpg images have locks on them

I have created a bunch of folder.jpg for all of my movie folders. When I view the directory all of the images show locks on the bottom of the images. Does anyone know why that happens and what I can do to remove them. BTW all of the jpgs were created with GIMP if that makes a difference. The lock does not show up on the images when viewed on the computer, just on the Hub when viewing the list of directories kind of like the Hub is saying that those directories are locked.

Thank you.

Did it start to happen out of the box or after an update?