I actually thought that one hour was about the right amount to charge, although I spent quite a bit of time - hours - mulling it over in my head, just for the fun of it. I do that a lot, but don't think it's fair to charge for what I consider entertainment. It certainly didn't keep me from my other activities.

(If I were involved in something else that took up my thinking time, I would not have spent the time on this until I did get an agreement. I do mention my billing rate in the first call.)