i had two spokes go on me and i didn't realise at the time. i was five miles from home having ridden a sedate 65 on a gentleman's club ride and it was one of my first rides of note after returning after a layoff.
i though i had lost so much fitness, until i got off and wheeled the bike into the house, and realised that the wheel dragging on the ground. i felt better after that and, as the rim was pretty concave anyway, junked the wheel.