The TPMS is a "dumb" system. Meaning... when its 80'F out and you set the TPMS target pressure... and then the temp drops.... the TPMS is still looking for that higher (tire)pressure, hence the light come on.
When ever you check your tire pressure... you should ALSO reset the TPMS so it knowns the new "target" pressure. You should be checking your tire pressure every third fill up anyways. But see the problem no one does, and Congress stuck us with this crappy TPMS.