If the Dentist says the tooth cracked because of grinding and not because of the filling he put in 2 weeks ago is this correct?

it is most likely the tooth had a small crack in it anyway. the tooth was alittle"high"from the new filling and the extra pressure from biting on it, cracked the tooth. usually after a new filling, you should go back to have the filling polished which strengthens the filling and adjusts the bite.