Thanks to all for the sympathy. I ache today in parts I didn't know my body had!
Not warming Mia up didn't cause her spook. Mia...spooks. She used to habitually spook and bolt. A few years ago, it was so bad that after 2 hours of repeated bolting, I tied the rein tight on one side around the horn and dismounted before she could get straightened out. After that experience, she spent 8 months without riding until I was able to hire a pro to train her from the beginning.
So in some ways, yesterday showed she is getting better. She spooked, spun hard, and then stopped. And she then stood still for 20-30 seconds, with the saddle way over on her side and me trying to move it back into place...but I had no leverage and the saddle was tight enough in retrospect that I had no hope of straightening it. I couldn't think of any way to correct things without bailing, and I knew bailing would scare Mia...so I bailed and rolled.
What caused it? Well, I looked the saddle over this morning. The latigo is about 3 months old, but I've swapped back and forth between it and a nylon latigo, so it might have about 6-8 weeks of gentle use on it. This morning, the smooth surface has a bunch of cracks running across it and the leather above the cinch hole looks very different from the leather after the cinch hole. My guess is that the violence of the spin, combined with my trying to stay on, stretched the leather enough to let it slide over her withers. The surface breaks are minor, so maybe I now have a properly broken in latigo. Or maybe I'll go back to nylon...
Another possibility - and maybe some tack people can say - is that the mohair cinch stretched some too.
And maybe the hole I punched left the latigo a little too long, although I don't believe in pulling until the horse passes out. Or perhaps the latigo WAS stretching all along, so the 'normal hole' was no longer the 'right hole'!
The other good news is that Mia looks fine. She has a nasty looking scrape and a cut on one hip, but nothing that won't heal. No limping, no sign of soreness, etc. When I went out this morning, she strolled over and stood next to me, yawning and nuzzling my hand...so I guess popping her in the butt with the rock didn't traumatize her too much!
I was feeling like quite the failure yesterday, but like jaydee said, I "survived to tell the tale. What more do you want!!!!
" And apparently I'm not the only rider who has discovered his saddle has done something it wasn't supposed to do, and I didn't come off her back until I decided to come off her back. So maybe...maybe horses sometimes make most of us feel foolish or incompetent, and maybe that is why a person can spend more years than I have left in my life riding horses and still learn something new.
Now I'm just trying to figure out how all those young folks write cheerfully about bailing off a galloping horse, when bailing off a completely immobile horse kicked my butt so hard! I couldn't be getting old, could I?