Assuming you kept that piece of paper, or recorded your mile splits in your training diary, you might compare to see if you're better able to achieve perfect pace. Tonight, skip the lamb chops and go for spaghetti. It is not important that you run this workout faster than the 20-miler run two weeks ago. Don't compare one workout to the next. More important is the fact that you were able to run two workouts this length within a space of 15 days.
Some coaches recommend just that, even taking runners beyond marathon distance.
I don't necessarily disagree with this approach, but since you signed up to follow my program, you'll have to peak at 20, not farther. The most important point of any training program is the totality of that program, and the results it brings. A flash speed workout with quick splits may look good in your training diary, but it could bring you to the edge of overtraining. The same with running the long runs too hard. Your time in the final 20-miler won't count three weeks later.