I went to the youtube videos and timed the starter and Bolt. For the starter, I have 1.69 after set for the semi and 1.68 for the final. Very consistent, which allows one to guess the gun. For Bolt in the final I saw movement at 1.56. On careful analysis, it looks like he was trying to time the starter, and just barely missed it.
Maybe he “blew his wad in the prelims” as Charlie once said about Asafa and really didn’t have it. So if you guess right, great; Otherwise FS gives a excuse rather than a loss to Blake? The loss in appearance money for losing could have been sizeable.