I have been asked about permission to pin by users privately and wanted to just say, you definitely have permission to pin, with a few stipulations!
1. Please make sure you are pinning directly back to my site and not an uploading copies of my PDFs.
2. Please make sure you are pinning back to the site and not the small jpeg preview of the PDF. (I am not really sure how you do or do not do this yet, but I have noticed the links on some of the pins out there, link back to the URL of the tiny jpeg, rather than the post).
Thank you for your support! And always feel free to comment on the posts or contact me via the contact page at any time!