This happened to me quite a while back, but I was just reminded of it this morning. It's not that strange - probably just a convergence of minor coincidences - but I've found myself thinking about it quite often since it happened.
One grey February morning a couple of years back I was travelling to Chester on one of those miserable trains that looks like an Eastern European tram (circa 1970). We were held up for some reason at Nantwich station and I was absent-mindedly scanning the people on the opposite platform when my gaze snagged on the figure of a young woman - late teens, or possibly early twenties - and I had one of those bizarre thoughts that appears to come fully formed, uninvited and absolutely out of nowhere: 'If I had a daughter, that's exactly what she'd look like'. Anyway, although this apparently independent thought had taken me a bit by surprise, I didn't really dwell on it; I looked again at the girl, shrugged mentally at the random nature of imagination, went back to my book, probably muttered something under my breath about the weather and public transport, looked at my watch, looked back again at the girl and did what you generally do in order to stay sane on trains that aren't going anywhere. (I should point out that at no time did I catch her eye, and I wasn't staring at her - I would swear that she didn't notice me noticing her.)
Anyway, there's a jolt, which I assume means the train is either just setting off or in the early process of falling apart, and I pull myself away from the book for one last glimpse of the riches Nantwich station has to offer only to see the girl on the platform looking straight at me with a big smile on her face and waving shyly. For a moment I'm completely taken aback. I look around me, but the carriage is virtually empty; there are a couple of people at either end, but I'm the only passenger in the entire middle section of the carriage - there's no-one else to wave to. I looked back at the girl - she still had her hand raised, so I pointed to my chest and pulled one of those 'who, me?' frowns, and she nodded.
So I waved back.
So, there you go. Nothing much really, but the whole episode still intrigues me.