Recently I was on the sofa with the bloke I was seeing when my phone went off and I picked it up and frowned and said 'what's she doing up? It's past her bedtime' (it was after 11pm)
He asked which friend was this and I was concentrating on responding so said the date we met in May 1999 and rattled off a brief potted history. He was completely astonished and asked how I knew this and I looked up from my phone in surprise and said everyone does this, don't they?
I know exactly when I met my friends, know when their bedtimes are, know their history.
To go a bit Tom Jones, it's not unusual? I sometimes have to remind my friends of their past history