Hustling versus Hurrying

[stegenref]

I've had several white hats this year tell me to slow down. But other things I've heard and read say you're supposed to hustle. How do you know when you're "hustling", but not "hurrying" too much? Where is that balance? And what's so bad about running fast?
The latest incident happened the other night during a JV game. I was the umpire and one team was kicking a try (PAT). After the ball was kicked, I turned around and there was no ball-boy or anyone back there to retrieve the ball and it had gone like forty yards, so I ran after it to get it for the HL, since I was the closest official to the ball. I like making sure the ball is ready for the kickoff team when they get out onto the field, instead of them waiting on us. Plus I like to keep the game moving along since I had a 45 minute drive home and the game had started late due to a previous game running over. Anyway, when I came back with the ball, the WH told me to "slow down" and "save some for later".