Hey Chuck, I hit that on a couple of things, but I did wait longer before going back to soccer and Tae Kwon Do.
Mine were: strained hamstring whenever I ran on the treadmill / did leg presses on the same day - from 8 months to 11 or so. Happened three times, each time when I did both the same day. Not anything huge, really just warming up with running (15 minutes or so, walk / run) and light on the leg presses (90 reps, 200 lbs).
No knee issues, but IT band issues off and on about the same time. I also scaled it back, kept up pilates core exercises and slide board just to keep moving, cleared up after about a week to two weeks each time.
Now no problem with doing any of that, soccer or combined hour of bag work with weights following. I think not all muscles heal at the same rate, some are problematic, or were either overworked or underworked (atrophy) due to the OA, so this is the kind of setback you see when you really start to push things.