Quote Originally Posted by Rusty Trichome
Perhaps you scuffed the end of the seed with the cotyledon a bit more than the end with the tap root?
I suspect this as well.
When you look at the seed, one end is blunt and has a scar where it was attached to the plant. The other is pointy. One edge is rounder than the other as well, and the place to scuff is the sharper edge close to the pointy end of the bean.