Delighted - 'cos I bounced back up, brushed myself off and looked around wondering if I had to say 'I meant to do that'! (The last time I fell off, the result was unreasonable in proportion to the event!)
The cause this time, pure operator error. Nice weekend morning, 5 of us, 4 wanted to take a little loop, I was feeling good and wanted to ride a little longer. I reached the agreed coffee stop after about another 45 minutes. Rolled up, no sign of other bikes. Rolled a little closer - 'is that Mark's bike round the side, lets roll a little closer, are the others there too, let's roll a little closer, yes it looks like everyone's here, oh goodness there's the curb right in front of me and I'm still clipped, a bit late for an unclip, oh oh now I'm stopped, good trackstand though I say it myself, try to rotate the ankle, no, not working, I think I'll topple gracefully to the floor'
That's how it should be done! (Didn't pass unnoticed, though)