The AA for your recipe is 75%, which is low. WLP001 is BRY 96. BRY 96 is one of the highest attenuating normal ale strains. Attenuation rates in the eighties are not uncommon with BRY 96.
As I have mentioned many times, a high krausen pitch will always outperform a "fermented out" pitch because the cells are in peak health and do not have to undo the morphological changes that occur at the end of fermentation. Add in sufficient aeration and a strain with a high attenuation rate, and an AA of 85% is not out of the question.
Are you certain that your mash was not stratified (i.e., hot on the top and colder on the bottom or in the middle)? A minute of stirring is often not enough to achieve an even temperature throughout the mash, especially if you had small dough balls.
Finally, as others have mentioned, one drinks beer, not numbers. In time, you will know what to expect AA-wise from a yeast strain in your brew house using your water supply. That knowledge will allow you to adjust your grist and mash profile to push AA in either direction.