MN/PE1<im ...and pain?

I have noticed a couple of times after doing the windmill, that my abs get really sore. No surprise there, of course. But it has also felt a bit... weird. Has anyone else noticed this?

I was going to do forward rolls and practice cartwheels today and it hurt really bad, over the lower rib - maybe more rib-ish pain, than muscular. I also noticed that I do the windmill towards the leading leg, rather than down between the legs (my bad) - but I don't get how there should bes so much pain, still. Can I have bruised my rib at the very bottom of the windmill? I'm not bouncing ballistically, either. Anyone else had anything similar?

I'm gonna do the exercise down between my legs from now on, but I was just curious - it's just too weird.