Lets look at the amount of water discharged.
If the stat was bad and the temp raised tp 210 degrees the T&P would open full bore and discharge until the water was cold enough the reset the valve...
There would have been a bunch of water discharged...
I'm not saying impossible or, they wouldn't require that safety function...
But I am saying unlikely.
Take the measurements both temperature and pressure. See what is going on. i would use a lazy hand gauge over a 24 hour period to determine the highest pressure reached.
Post back with your findings...