When people know each other in a city with 5 million population, you begin to feel ok about it. That's because you have been living here for all your life, went to school, graduated from university, had several works. That's just normal when it comes out that your new acquaintance knows some of your good friends.
But! When two people you know,of different nationalities, living in opposite parts of our earth, having nothing common, just meet when the chance is so scanty, that's seams incredible. And you pretend that you're taking part in some movie, "The Truman show" for instance. You are shocked for a while. But later you get used. Because it's inexplicable, but our world is really so small.