Going to apologise to someone you've just been talking to very shortly after having bid them fairwell, for something you didn't realise you'd done wrong.
From the so-called "Bigotgate" affair (28th April 2010) during the 2010
UK General Elections, when PM Gordon
Brown had to apologise to a
lady in Rochdale he'd just spoken to, for calling her "bigoted" after he had spoken to her and got in the
car to leave, not realising his radio mic was still on.