Such as why the bolshiest choir members are an absolute pain to work with on their territory, yet suddenly turned into happy, amenable, co-operative people on my territory.
Admittedly we were learning something I was incredibly familiar with and they weren't.
Admittedly, I went into incredibly well-organised teacher mode and didn't give anyone a change to do anything than draw necessary breath.
Admittedly, there were a larger number of us than I dreamed would ever do this mad thing we are trying to do and they may be overwhelmed by that.
But, I am still shocked. Delightfully so, but shocked.
There are other mysteries, such as how come it's only taken me 35 minutes to prepare next years budget when it's usually a full day's job at least, why I'm still awake after a long day, why I'm so slow at realising it's going to be so much better all round for me to stop trying to be something I'm not...
And why I'm getting excited at the thought of going to watch 30 men playing with an odd shaped ball at the weekend!!

