He is grieved, maybe, at your language, but that is because he is thinking of you--the possible effect of it upon your future.

To try and stop you, he offers you another four sous.

The story is told of a Frenchman who, not knowing the legal fare, adopted the plan of doling out pennies to a London cabman one at a time, continuing until the man looked satisfied.

Myself, I doubt the story.

From what I know of the London cabman, I can see him leaning down still, with out-stretched hand, the horse between the shafts long since dead, the cab chockfull of coppers, and yet no expression of satiety upon his face.
But the story would appear to have crossed the Channel, and to have commended itself to the foreign waiter--especially to the railway refreshment-room waiter.