Your colt really isn't exceptional Duritz. The author quotes a 7 day study by Dr M Tischner who found that of the 7 stallions he watched (using a flashlight at nights) they had an average of 7.4 erections per day, 3.8 full erections and attempted to masturbate 4.1 times. The stallions spent 38 minutes a day on average with an erect **********, 19.5 minutes of this time was spent masturbating. Sue McDonnel however in her study found an average of 18 erections a day in stabled horses, 75% of them including masturbation (broken down in to 83% bounces, 57% presses and only 13% pelvic thrusts). This book doesn't skimp on detail. However ejaculation was only observed on 4 of 447 occasions so maybe your horse was good performer - outside the stalls at least.
Unfortunately sexual signs are not a good omen for the horses winning prospects. Perhaps you should consider it for breeding.

KV