While this doesn't appear to be as close as the incidents in BOS, AUS and JFK, it is concerning that another jet aircraft began a takeoff roll at a busy airport without hearing the magic words "cleared for takeoff ". But the other three incidents were about as serious as one can have short of an actual accident. One analysis determined that all three incidents were 4 seconds OR LESS from two airplanes occupying the same space at the same time.