How did I never pick up on this before.
The wall outside Graceland is covered with handwritten messages. The Graceland folks don't mind but they do go sandblast the wall clean every few months. Elvis is a Mormon was on the wall.
Did you ever meet a character who called himself 'Doc Holliday' in the Southhaven area? Or a Graceland tourguide named Ga?
One of the popular places for Missionaries in that area to visit while on their mission is Graceland. So I have no doubt you saw that message. As for "Doc Holliday" no I did not but I did know some Hollidays (older couple). Also I went to Graceland 3 times and never paid any attention to the guides names.