Thats sounds about right... i had a jack herer that kept turning herm on me about 8 weeks into flower... i had the hps at about 12 inches with no signs of burns or heat stress... a friend of mine said back the light off.... so i moved it to about 20 inches on the next run and everything went smooth... i even grew out the seeds from the hermie... and i didnt even get a nanner... good smoke too