OK, here's my real theory.
He only does it when he's REALLY pushing it. I mean, to pass the leading rider, on one of the last laps of a race in the premier motorbike racing series, by delaying your braking that extra little bit, you gotta be on the ragged edge of traction and control. We know Sete or whoever doesn't want to be passed, and he's no amateur. So maybe when he's pushing that hard, and coming that close to sliding out, Rossi just feels a subconscious need to put his foot out. It may be an involuntary reaction, a Pavlovian response, a subliminal attempt to brace himself for the fall.:scared
Theory 2: Rossi is such a showman that he does it on purpose to get people like us discussing it at length on internet forums. I'm sure he browsing this thread right now, laughing maniacally...:lol :epimp