Pass interference restrictions don't begin for the defence until the ball is thrown, so there probably was no foul in this play at the 26 yard line. If this had been a down and out/in or a hook and you think you've got DPI qualifying contact at a specific spot that is less than 15 yards from the LOS, absolutely a spot foul; but a fly pattern that ends with an incompletion at roughly the 38 yard line, I would go with a 15 yarder all the way.