Re: Mistakes that taught you a lesson for life!
thinking of the blunder you did...I fear I did something similar at least a hundred times, and what is worse, no one ever told me how impolite it is, they are certainly always tolerant and let me get away with it. But I see what you mean and will try to improve (just take more time for the bow instead of running off).
Other mistakes - I should think about. There are lots of horrid blunders and mistakes I made out of the dojo, but just now I don't remind anything really bad on the tatami.