A book goes on a round the world trip

In 2002 during a trip to Sydney, Australia from the UK, I visited a secondhand bookshop in Cronulla. The owner asked me what sort of books I was looking for and what I had read recently. I mentioned The God of Small Things by Arundhati Roy as a book I had recently enjoyed. The owner went straight to a shelf and pulled out A Fine Balance by Rohinton Mistry and having read the blurb I went ahead and bought it. About a third of the way through I came across a boarding pass and was surprised to find a familiar name on it, my sister's initial and surname. At first I just thought this was a minor coincidence of someone with a similar name, but when I looked more closely I saw that the outgoing airport in the UK and the destination in Turkey fitted with a trip my sister had been on. When I got back to the UK I asked her if she had read the aforementioned book without mentioning any other details. She said yes, she had taken it on holiday to Turkey but never finished it as she wasn't enjoying it. She then left it behind.... and somehow it found its way to Australia and a secondhand bookshop in Cronulla where the owner recommended it to me and I bought it. On a subsequent trip to Sydney I visited the same bookshop and told the owner the story. She was absolutely blown away. Oh, and by the way, I really enjoyed the book and still have it with the boarding pass tucked inside. My sister also sent in the same story to Radio 4's Book Club a couple of year's ago and was invited to relate it on air.