That happens, since fermentation is exothermic (produces heat). It may get even hotter before it lowers when fermentation tapers off.
Many of us keep our fermenter in a cooler spot, like a basement.
What I do is make a water bath in a big cooler, and that helps keep the temperature more stable. Even at room temperature, it takes a LONG time for the fermentation temperature to raise enough to heat up the water bath, which in turn keeps it from getting so warm. If it does creep up above 70, I drop a frozen water bottle into the water bath to cool it down gradually.
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