Cody's Spirit Is Fading Away ....
... go and visit his resting place to keep him in this world - or words to that effect. Is this a new interaction, as I've not had it before?
Forum Discussion
It was implemented in a patch some time ago. Basically, you click that interaction on Cody's tombstone if you want his ghost to remain in the world. Otherwise, he'll disappear (though his portrait might remain if he's part of a family tree; I can't remember because I have MCCC set to not cull ghosts).
