What happened to my leg this morning?

Came to the gym about 5:40 ish this morning because I was irate and needed to blow off steam. [[Finished just before 8:20am, I dont know if that matters or not]].

Was doing 230lb squats, which I've been doing for a while, with no issue, until today.

Halfway through my first set, it felt like a string snapping on my thigh but I swear it was a muscle. I finished the set, even though the "snapping" happened each time I squatted down.

Stopped for about 2 min, lowered my weight to 180lbs, happened again first 2 reps. Took another 2 min break and finished my sets with no further problems. Yet, I'm concerned because I've never felt anything like that before.

Any idea (s) what happened?
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P. S. The "snapping" did not hurt. It was faint and felt like someone was snapping a very small/weak rubber band against my leg.
What happened to my leg this morning?
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