It seems that I have a pulled muscle in my right hip. I first noticed it after the Sprint at RIT on Aug. 6, then it was more noticeable after the Middle at Mendon on Aug. 7. I played pickleball on Sat. Aug. 8, and it was distinctly worse on Sunday.
Update -- I changed this to "recovered" on Oct. 25. It's not totally recovered, but I can play pickleball with minimal aftereffects. Next thing to try is some short slow running.