Try the following: enter an Event and after you win a race (when the big green 'win' pops on the screen) and before you are being automatically redirected to the Event menu, hit . Then you will notice that Trigger considers that you have forfeited the current event (even though you have already won it!) and allows you to re-try it.
I believe it would be fairer if the win were recorded and remembered in either case: waiting patiently for Trigger to redirect you automatically to the Event menu, or impatiently hitting 'esc' to go to the Event menu and continue to the next race. (On a side note, this would become important for Single Races, too, when caching of best times is implemented.)