I don't! I have in the past given myself sore jaw muscles by lying on my front and holding my mouth slightly open to prop myself up on my chin, but it's been years since I did that!

I'd expect this to be on both sides, if it were something like that-- my left side is totally unaffected. Even now, today, having eaten nothing yet and not aggravated it, but not having taken ibuprofen either, my left jaw hinge is normal and my right jaw hinge is slightly taut-feeling and warm to the touch. I feel like maybe there's an injury in there or something. It's weird.