Azfiddle - thanks for your story. We will likely never know what caused it, but I was pretty good at starting physical activity without warming up there for a time, got a little overconfident I think. I deadlift close to my body weight, and squat more than my weight and I suspect that this tendency of mine is at least related to it...

I did go for a gentle hike today, and yeah, it came and went. I am still trying to justify going to spinning class tomorrow night and just spinning lightly... I cannot swim, and I've got to get SOME real exercise to keep my blood sugar in control. I do not take medication for the diabetes. Hopefully just a few days off the bike won't mess things up too much.

Thanks all for the good advice. If resting doesn't show improvement by Thursday will see my dr. Friday.