I know that stuffing the loin increases cook time but by how much? If everything is almost cooked then the 6 minutes you had the tenderloin in the skillet should have almost had it done, didn't the 40 minutes in the oven get it overdone? I have put whole tenderloins on the smoker that goes at 235 degrees, and usually 30 minutes or so will get them to 130-135 degrees.
Were yours medium, well done, or what. Just curious.