Summary: The album had been reset to the default visibility settings for albums.No diff available.
I created a new album on Facebook and picked a particular list of people to share this album with. I used iPhoto to share pictures on Facebook using this album. After some clicking back and forth I noticed that my album was no longer restricted the list of people I had picked! The album had been reset to the default visibility settings for albums.
What a major fuck-up!
I have resolved to delete all the Facebook albums with non-standard permissions.