You can't use my artwork unless you ask me!

"Good morning!
Just wanted to let you know that I added one of your works as my cover page. I have attached a link to your page and hope you see an increase in traffic and visibility to your work. I love your work! Enjoy the day!"

I was welcomed this morning with this FB message. I was horrified at how the general public treats artist's work as something they can just grab and use because they like it. I asked her nicely to take it down and she stated that other artists had reacted  in a positive manner. I explained how the copyright law works and that her usage was against the law. I checked out her supposed "link" to my web site worked, when I went to check it out. It only linked it an image she had saved to her photos. This reminds me yet again that I really need to include copyright info on every image I post. This is a wake up for me and I'll be more careful in the future. I promise myself!