2000 ford explorer got real hot for a minute then went back normal?

On my way to work after only 10 mins i noticed my check gauge light was on. Looked down an my temp gauge was a inch away from the red hot mark. I noticed it was kinda jumping a little, so Iinstantly blasted the heat it went back down got on the bypass and turned the heat off and it ran normal temp the rest of the way to work.

2 things may have caused this, I overfilled the resouvour with antifreeze 2 days ago. Also my bro admited he drove it hard kicking it for a few minutes the night before.

So what could be some clues? Sticky thermometer or overfilled with antifreeze.

Never have had this issue before its got 191k on the motor n has had new heads n radiator put in at about 130k.

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