K, got the valves back. The stems are totally straight from what I can tell. The burned valve is a tad deformed; albeit, uniformly deformed... not bent or lopsided. It appears that it has been essentially been getting pulled through the head to the point where the diameter is smaller than original as it has sort of mushroomed up. 7 of the 8 valves measured are 32.02mm to 32.09mm in diameter. The burned valve is 31.71mm. Maybe this is attributed to blow-by erosion on the valve too.
I would like to think this was due to abuse or something environmental as I don't want to have to deal with this issue again if I should keep the car for a long time. But wishful thinking hasn't served me too well so far.
The thought at the dealership is that either the valve was too soft or there was some sustained high rpm driving by the previous owner... or something else like an out of spec spring, anyway, here are the pics.
The first one is one of the OK valves. The black one is the burned valve. (duh)