Update - October 2009
Just wanted to say that I have had a similar experience as the witness from May 2009 at the Runnymede Theatre/Chapters.
It was 2005 and a friend of mine and I were downstairs looking for a specific book. We kept finding books of the same topic and similar relation but not the one she was looking for. The minute we gave up and decided to turn around, a book fell off the shelf (mind you, no one was in the isle with us). It was exactly the one she was looking for.
Whatever it was definitely helped us out!