Looking at those numbers, tells me he could have cert'ed the card at too low of a temp. LT1's OEM operating temp is 210-220. Likely once it heated up (last pull) it was making peak power.

I had a big talk w/ Al yesterday about having some talks on the forums about being very deliberate and accurate w/ your dyno procedure. Adam was always very good about having group dyno days and surely this was one of the reasons - to point out where flaws were being made in the process. Water and oil temp, trans temp, diff temp, air pressure in the tires all play a big part in the number displayed. Using the same tire pressure gauge as well.
I likely have over 100 pull's on my CMC LT1 motor and it has never surprised me w/ odd numbers. I've dyno'ed in the winter cold, summer heat, at 200 ft, 1200 ft, and 6000 ft. I've always been with in about 1-2mm plate size of where I was the previous year or previous dyno.

I'm not saying Kent wasn't, but you have to wonder if it was a contributing factor.