This young woman came up to me - brazen as you like - and hugged me in the street the other day. She kissed me, too. On both cheeks. To tell the truth, I didn't even know her name - though she knew mine.
If you are, or have been a teacher, this touching scene won't surprise you in the least. However well you know the names of your students at the time, once they've left and gone out into the big wide world, it only takes a few months for them to be totally wiped from the memory bank.
Teachers seem to be different in this regard. Tests show that the average person can learn and retain huge amounts of information. But for the teacher, the only way we can absorb each new set of names is to obliterate all the previous ones mentally.
So let's call her Lola. After her access year with me, she'd gone on to a degree course at university. When I bumped into her she'd just heard that she'd achieved a good upper second. Hence the spontaneous outpouring of joy.
But these days, you might have noticed, you don't actually need to be happy to kiss someone you hardly know. Over the past 10 or 15 years, our culture has become so much more tactile. Social kissing, once the preserve of those excitable foreigners, has become the norm.
For some - and I have to confess to being one of them - this transition has not come easily. While the Anglo-Saxon stiff upper lip was always something of a stereotype, it's also true that stereotypes don't come out of thin air: they are based upon something.
In the home where I was brought up, we simply didn't touch each other from one month to the next - unless it was an accidental collision or a crafty slap. The idea of actually kissing on arrival and departure would have been seen as strangely exotic and slightly dangerous.
In the 1980s I went away on a teacher exchange and didn't see my mother for a year. Did we fling our arms around each other and embrace and kiss for five minutes on my return? Not quite. Though my mother did say: "Oh, you're back." From this I knew she was hugely excited at seeing me again. She never normally came out with such emotionally charged words as "Oh".
Like the rest of us, she too had to make some gesture to the emergence of the kissy culture. To this end, she developed a way of holding up her cheek to be pecked at by her offspring. You could tell that she was only doing it on sufferance by the awkward way she stood and the look of fear in her eyes.
To be honest, I haven't always done a lot better myself. Apart from anything else, there are so many potential pitfalls. As social kissing is still a work in progress this side of the channel, no one set of rules has yet emerged. In France, it's easy. One side, the other side, and you're done.
But who knows what the norm is in Britain? Stop at one and you're considered cold and testy. Get up to three and you're a dirty old man. More crucially, do you start on the left or the right? Fail on this one and you can end up with a serious case of concussion.
Now I've discovered there's a whole new phenomenon to take on board: the man hug. I received my first just the other day and, I have to report, I wasn't ready for it. I don't remember my father ever touching me, except perhaps once when he gave me a whack for trashing the front room.
So what do I do when it's a former male student I notice progressing up the high street towards me? Rush forwards, throw my arms around him and say: "Glad to see you, what's-your-name"? Or do I just push out my stiff upper lip, turn on my heels and walk firmly in the opposite direction?