I am VERY happy to report that the tight sartorial muscle did NOT repeat itself last night My gut instinct that it was related to the combination of spinning after doing a bunch of lateral hip exercises seems to have been correct. I won't be doing THAT again...especially after I had the same result both times I tried to combine the two. There was a period of about 3 weeks between each attempt, so I think that seems a pretty strong indicator.

My knee is also starting to feel better