As far as I know…he just got a cramp in his hamstring. He didn’t the 4x4 because if you don’t finish one event, you can’t do any others… He tried to run the 400m in the Nike Mawler… if you’ve ever tried the spike you’ll know it’s not for the 400m. It’s for professional 60m sprinters… 
2009 USA Outdoor Track and Field Championships Official Website at TrackTown.net… if anyone wants good quality videos from the US trials.