I didn't actually have a "free day" on Amazon on Wednesday, Sept. 11, 2019, although I did give away a copy of Improvising to Beat the Band anyway. When I looked at Amazon that day, my book wasn't listed as a promotional day, so no error there.
A big thanks to whoever it was who had system administration privileges to download it! Like I mentioned in my acknowledgments, I appreciate the encouragement. I hope you get as much out of reading it as I got out of writing it.