Um, I hate to break it to you, but those aren't actually rare. Admittedly, they're rarer than, say, an ahea egg, but they're still found every day.
So it's lucky, but not really epic luck. :)
I've had to go on a unplanned hiatus and will not be able to get on much, if at all. I apologise for any inconvenience this causes you! If you really need to contact me, I may respond to rmails.