The shield is still up! Bob has the situation under control, and is explaining it to his partner, Alice. While he initially thought everything was fine and going to plan, it's only once he stops to think about it and hears himself say it aloud that he realizes how much trouble he and Alice are really in. Essentially, a case of in-universe Fridge Logic or Fridge Horror catching up to the characters, can be played for laughs or drama. If the character doesn't realize how screwed they are until after they're done explaining, it's Delayed "Oh, Crap!