I take seller stories with a grain of salt. They'll even make up fake stories for authentic autographs to enhance appeal. What sounds better? "They came from a family friend," or "I hit her up through the mail several times."
Steve, you're absolutely right about seller's "stories". In fact, one of the 4 postcards from Harper Lee that I posted was sold more than 10-years ago. Soon after selling it, Ebay seller "global-photo-archive" listed a signed copy of TKAM along with a reprint of a signed photo of Harper Lee, as well as a reprint of my postcard. In the item description the seller claimed the postcard had been received by their aunt. Here is a photo a saved from their listing as well as my scan of the postcard.