Both my 150SE's were running very warm/hot. I even put a quiet computer fan near one because I was worried about thermal shutdown, or reduced equipment life.
But, in talking the issue over with Dan, he indicated that he now biases the amp at a lower level.
He brought the high bias setting down on both amps, with absolutely no discernable effect on sound quality.
And both run much cooler now.
I strongly recommend you talk with him. His product service is fantastic!