Hey, Steve! Did you move kind of suddenly at the time this pull happened? I'm older than you are, and I'm not a pro arb, but when I was climbing on a fairly regular basis I would get massive muscle cramping at night, especially when I moved my legs too quickly. After what was for me one particularly long, hard day of climbing, I didn't even make it home before all of my legs started cramping up, especially my quads.
Butch from the Tree House forum gave me the answer that made the difference; like night and day. He told me to drink at least two bottles of Pedialyte electrolyte drink per day, as well as eating bananas, which have potassium in them. He recommended drinking one bottle before starting work for the day, by way of getting ahead of the game, but I usually just drank it as needed in the tree, and finished the rest of the two bottles after I was done climbing for the day. The Pedialyte replaces the electrolytes in your body that you lose by sweating.
After drinking two or three bottles of that stuff (usually only two, maybe three on really hot days), and eating a few bananas, my symptoms of massive cramping disappeared nearly completely. Without it, every little sudden move I'd make while resting in bed would trigger a charlie horse, or muscle cramp. Usually in my calf muscles, but also in the hamstrings and the quads. The difference was just amazing.
So, my suspicion is that you might have gotten a really bad muscle cramp due to dehydration, and that drinking the electrolyte drinks might help calm those muscles down, and prevent them from pulling again. The Pedialyte is expensive, but the house brands on the shelf in the baby care section of the supermarket, usually next to the name brand, probably cost half as much, and work just as well.
Powdered electrolyte mixes are also available from Amazon, and cost maybe a third of the name brand pre-mix bottles, but it's more work and doesn't taste as good.
Hopefully I haven't already covered all this in previous threads with you, and I'm not beating a dead horse, here. I would say you should spring for the expensive stuff for a few days, and see if it makes any difference, along with the bananas.
If you do decide to try it, I'd love to hear the feedback on it. Maybe in this thread, since this is where the initial suggestion was made. Thanks for listening.
Tim