Costco Copyright Consent Form

I paint a lot of pet portraits on my iPad. The end result is a JPEG image that is sent to the email address of the person who commissioned it. A lot of people print the image themselves, or upload it to a website to have the image processed in to a conventional mat and frame, or in to non traditional products like t shirts, coffee mugs, or totes. Yesterday I received a copyright consent form from a customer who wanted her image created through Costco. This has never happened before, so I found it interesting.  Costco wanted a signature from the artist approving that the work go forward. They noticed the initials and date I typically sign my portraits with on the right lower hand corner. I couldn't fill the consent form in with either on my laptop or iPad, so I printed it out and took a photo of the image, along with the portrait I painted for her, combined the two, and sent it back. I'm hoping this approach will work for her, particularly since she is a repeat customer.  It makes me wonder how many times people abuse an artist's work, but it's nice to know someone is watching!