He was controlling the speed of the down side movement, probably afraid to fall off. I've seen other dogs fly off the end before the board hits the ground, which is an automatic fault and can be extremely dangerous.
Early advice I received from others to correct this behavior was to:
1. from Tracey R: Lure him to the end with a treat. (that works, but only when luring him)
2. from Jane S-M: Stick a sticky treat on the end of the board for him to run to and get no matter where I may be.
3. from Cindy D: Treat at the very end of the board, at board level, at the moment the board hits the ground. (this has worked very well, see P.S. below.)
The 2nd method worked out pretty well at first. Sticky treats are covered in my blog post, Dog Treats. Max ran to the end every time without hesitation, gobbled up his treat, and waited for a release. My fear is that sometimes he'd start eating before the board hit the ground, and a few times has nearly fallen off. Also, when I don't put a treat there, he sniffs around looking for it, licking up the sticky residue from the previous treat, and is often too preoccupied to come when I release him.
His hesitation only lasts for a few seconds, but in the competition world, if two dogs both Q, the one with the fastest time wins. A second is a second. As a great old sailer in Mandeville, who used to win every weekend's sailboat race, once told me : "Few people appreciate my secret, but:
"A foot's a foot, and every foot you can shave off counts."
So if I'm going to compete, I might as well try to win.
P.S. Added 11/9/20103rd choice is what we use now most reliably. Maxie runs quickly out to the end with me running alongside. The second the board hits the ground and makes the banging noise, I present a treat from my fingertips, at board level, "as if it was growing up from the ground". I am careful NEVER to present the treat up in the air because I want D's nose to be down, which lowers D's center of gravity and improves balance. I am also careful not to place my arm across D's face, so I present the treat with the opposite hand from the side I'm standing on. Gradually I have faded out the treats as the "run to the end" behavior became habitual, sometimes treating, sometimes calling off before treating, sometimes not treating at all, and sometimes not running alongside at all. Maxie is nailing the correct behavior no matter where I am on the course (ahead, behind, on the side) up to about 20' away, as described in my Around-The Clock See Saw Training blog post.