This line has never made any sense to me
*clears throat and pulls out binder labeled The Sound of Music Explained*
Captain von Trapp is used to calling the shots around his house. Now, Maria has come into his house and blatantly disobeyed his orders, taking authority for herself. He, seeing now that she has this authority, has subconsciously recognized it and blurts out the line in question because he’s flustered and angry
and distracted by a soaking wet nun.
That’s why she makes that face. She knows she’s gaining something here, she’s got some serious respect from the man who was originally going to summon her via whistle. Now they both know that she knows that they are on a level playing field and that he is actually listening to what she is saying he just doesn’t want to hear it.
*puts away binder and dusts hands* Thank you and good night.