I have cut comic book backer boards down to envelope size and put my card(s) on it, secured with photocorners and my address on the back. That way your item has a matching SASE that can be used to match your card to. It also keeps your card from getting bent. I have also put my name an address on the hard plastic top loaders as well. Just a suggestion when mailing to someone who is not a quick responder.
I wonder if it could be a stamp or autopen. That looks like his sig, but he never signs for free. I hope that its real, but it just seems odd that all of a sudden he is signing for free. Hope the card you sent was worth much money considering you didn't get it back.