Ahh, yes, I believe there is a border. I only found that today in the corrections on the website. It wasn't in the original pattern, but looks like a small border in the picture.
Here is the link:
I did get ahold of a friend since I posted who explained it as, if you have 5 sts to the inch, you are only off 1/5 inch. She also said blocking can make the armholes look even.
I would have thought it would be BO 6 at beginning and end of row then do the dec in the same fashion. Why wouldn't this work? This just sounds neater to me.