A reddit user figured this one out for me.
He was totally right.I'm with @ojuiceblue on this one, the issue towards the heel is either a uneven primary grind, or it would be fixed with a sharpening choil.
If you look at the very end of the cutting edge you can see where you ground into the ricasso, or plunge line, the slope down from the flat bar stock to the final edge. Once you ground through that, you were probably fine from that point on (which is why you ended up with a good straight cutting edge), but before that, your stone was sitting at an angle and riding on its edges...and i would bet that wide spot is the width of the stone away from the heel.
In other news, I successfully Sharpened my 8" Chef's knife and 7" Santoku today with the same progression at 20°, and am very, very happy with the results.
Still have to practice my freestanding paper slicing technique , but this is definitely the sharpest I've ever gotten a knife. Stoked!