True. First there was Owens, then Lewis, now Bolt.
BTW, here's something interesting on the subject from Wikipedia:
http://en.wikipedia.org/wiki/40-yard_dash
"Furthermore, the use of hand-timing in the 40-yard dash can considerably alter a runner's time; the methods are not comparable to the rigorous electronic timing used in track and field. 4.2 and 4.3 second 40 yard dashes are not unheard of among high school athletes, and it is estimated that Usain Bolt could break the 4.00 mark.
Darrell Green, who ran one of the fastest 40-yard dashes ever at 4.09 seconds [1], had a collegiate best of 10.08 s in the 100 meters.[2] Justin Gatlin, who ran 9.85 s for a gold medal at the 2004 Olympic 100 metres, has a verified 40-yard dash best of 4.42 s.[3] This reflects the difference that timing methods can cause to a runner's time. However, this disparity could be caused by differences in endurance as well."