No, nothing like that. I'm betting it was all the strange lifting and pulling to put away all these Xmas decorations (I have 6 or 7 tubs of decorations, two trees, another dozen boxes, etc). At one point I remember bending over the back of the couch and twisting to reach a cord, but I didn't feel any pain at the time. Could have just popped out later, having been pushed slightly out of place at the time. But the problem is that if you turn over during the night, it pulls it into weird twisting motions which cause severe spasms. So then the other muscles lock up to stabilize the rib, using the other vertebrae as anchors. So eventually those powerful spasms pull the rest out of alignment. God that x-ray blew my mind, but confirmed what I suspected. The lower thoracic vertebrae looked like they were stacked by someone shaking with Parkinson's!
So now it's 20 minutes of heat, 20 minutes of ice, 20 minutes of heat, 20 minutes of ice, repeat, repeat, repeat, repeat all night. And sky-high doses of curcumin and a few other natural supplements. And a lot of stretching work. I figure this will take me a good week or two to really get back to fully normal. Lots less pain today though.