A point of clarification: I was not upset at all over the fact that the documents were protected. What annoyed me was the fact that I had been using the images for a number of months with no notice or response from Pixabay.com and suddenly they put their notice on all the images going back months. If they had given the notice immediately, I would not have been making the same mistake over and over again.
When I use images that are not my own, I either scrupulously abide by the copyright and license restrictions or use image clearly in the public domain. I found a website, Pixabay.com, where the images are clearly marked as "Public Domain." I used quite a few of their images over a period of time and had no problems. Then suddenly, the website retracted all of the images and put up what was essentially an advertisement in the place of each photo and further implied that I had used the images improperly. As a result, I have gone back through my posts and removed all of the photos I could find that came from that website.
If you come across a blacked out photo on any one of my posts, please leave a comment to that effect and I will immediately remove that photo. Thanks for your cooperation.
I suggest that extreme caution should be exercised in using any images that are not clearly marked as in the public domain or that are old enough to be out of copyright.