These are probably being rejected from the free section. The option to have your images considered for free section may have been changed (checked or unchecked) without you realizing it. When you are doing your next uploads, make sure to check on that.

Thanks for the explanation.  Now ... I do not want any image going into the free section as everything I've uploaded are all selling well elsewhere.  I looked at the site and cannot see where I can opt out of the free section.  How do I take images out of the free section (I just got a notice that some images have been moved there) and how do I prevent this from happening to future images?

Every once in awhile, our setting gets changed and we end up with images in the free section. I go through and delete the files after I receive that notification. Keep an eye on things when you are submitting/uploading/indexing to make your life easier!

They definitely have some sort of glitch in their system. I had all my files turned to exclusive images and some of my files turned into the free section also!
I had to manually go through each and every one of my files and change the status manually. 
The couple that magically turned into the greyed out check mark of the free section had to be deleted even tho these were good sellers of mine! 
Now i uploaded back these deleted files and of course no sale yet and losing the good exposure prob doesnt help much either.