I can see a few things from your post that look suspicious.
I looked at the build diagram on this site:http://www.hamuniverse.com/ae5un2mextremebeamQuadantenna2.pdf
The loop dimensions you posted are very different from what is on this diagram? Maybe you built a different antenna?
Ref: 82-1/2" 84" (This is the back of the antenna)
DE: 78-5/8" 80-3/4"
D1: 74" 75-1/8"
D2: 72" 74-1/8"
D3: 70" 73" (This is the front of the antenna)
AE5UN's diagram has these spacings between the elements.
Ref-DE = 14.5"
DE-D1 = 9"
D1-D2 = 12"
D2-D3 = 18"
It's hard to tell from your flickr picture but you should double check the element spacings and position on the boom.
I think that using the nut and bolt to connect the ends of the element loops is a very poor idea. It leads to uncertainty on the element length. Why did he not put the total loop length and overlap the ends and solder? That would be much more precise. This diagram does not put details on the bends. Also the bolt is likely to lead to corrosion and poor connections. Probably the loop lengths will need to be modified to include some extra length (~1") to substitute for the bolt.
The other problem with this design is that the coaxial cable runs too close to the elements and is in the same plane as the polarization (vertical). This will distort the pattern. The coaxial cable should be dressed along the DE spreader to the boom, run down the boom past the Ref (the boom should be lengthened by 2 ft past the Ref). Make a loop at the the far end of the boom past the ref and route it down the mast. This keeps the vertical run of the coax behind the antenna. Vertically polarized antennas should have the cable to the rear of the antenna.
It could be that this antenna is not a very good design in other ways. I did not take the time to analyze it.