It's not only unusual, it's basically mandatory with today's engine regulations. With the race in hand, the team will dial back the revs, and the driver will short-shift. With a 15 second lead, who cares if second place gains 3 seconds each lap? This leads to skewed margins of victory, making the race look closer than it was, and giving false hope to fans of the 2nd place driver. Case in point: at Melbourne, the margin of victory was 1.8 seconds. Tell me, was that race ever in doubt? It only looked close at the end because Alonso closed his eyes and took one hand off the wheel for the final few laps. Even so, people delude themselves about the chasing driver's abilities...