Three possibilities
1) He was cruising it thinking it was an easy mark and now we'll see some real effort and he'll make it...and why not? He doesn't look tired. He may just be...good at this.
2) The above...and he breaks, either to return to old mileage...or period.
3) Something untoward is happening. If ever there was the need for boots (Boots?) on the ground for a solid week it is now. Not necessarily to "bust" WG, but to vindicate just as much...