Having been busily engaged on a mission of huge significance (to me) and of no significance whatsoever (to everyone else) I had not been to my favoured coffee joint for quite some time when I stood being attended to by a rather flustered young man struggling with the touch-screen of his till.
'I'm sorry,' he said, 'I am slow because I am new.'
'That's okay,' I replied, fumbling to extract a plastic card from my wallet, 'I am slow because I am old.'
He looked at me and I looked at him and we smiled at each other.
'You wouldn't call yourself old if you could see my grandad,' he said.
'Well you wouldn't call yourself new if you could see my pal's new son,' I countered, somewhat lamely, I thought.
'Oh for goodness sake will you two get on with it,' came a woman's voice from just behind me.
I turned to face her, feeling a touch of grumpy old man irritation rising, but then I saw that she was smiling.
'And are you old or new then?' I asked her.
'I'm middling,' she said.
And I looked. And she was.
That's all. Just a brief exchange between strangers.