A precedent "broken" in Casablanca

I watched part of Casablanca last night for the umpteenth time, and for the first time noticed a rather trivial error in the dialogue.  In an early cafe scene, Victor Laszlo has arrived with Ilsa and invites Rick (who never drinks with customers) to join them...

Laszlo: Won't you join us for a drink?
Renault: Oh no, Rick…
Rick: Thanks, I will.
Renault: Well … a precedent is being broken.

Later in the same scene, Renault uses the word improperly again:

Waiter: Your check, sir.
Rick: No, it's my party.
Renault: Another precedent gone. This has been a very interesting evening.

I'm not the first to have noticed this, and it in no way affects this wonderful movie, but it's the sort of thing that nitpickers and grammar Nazis love to encounter.

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