I would only be concerned if they had removed you from your original confirmed flight and you didn't get any standby before then and then not able to make the original flight. Any flight you got before your original flight is a bonus for you. If you got home at your original flight or earlier from a different successful standby, don't ask for anything, and I don't think you ore due anything. But if it screwed you up and you got home later than your original flight, then you would be due something.