I'm an idiot.
I did all 5 of today's sets just fine: 20, 18, 15, 14, max > 40. In fact, I maxed at 45! However, I misremembered one thing: today everything changes. The rest time drops to 45 seconds instead of increasing to 90, and sets 1-3 get repeated. So today's sets were supposed to be 20, 20, 18, 18, 15, 15, 14, max > 40. That's a whole different story.
Oh well. I guess since I'll be doing this week again I'll just do it right next time around. Friday will be pretty tough, though: 18, 18, 16, 16, 14, 14, 12, max > 40. I guess if it were easy, it wouldn't be very fun to do...everyone likes a challenge now and then, right? And I wouldn't really go back to weeks 1 or 2--they'd be too easy now. But don't think that'll stop me from moaning about how hard future workouts sound. :)