I think it will depend on where abouts in France you were flashed i.e. which department.
I've only ever been flashed in Provence in France and never heard anything about it, but I would be very surprised if Alsace are so forgiving.
Similiarily, in Germany, I've been flashed up near Hannover and got away with it, but when I was flashed near Karlsruhe, the Polizei there were quite happy to contact me through the Zh Polizei and send me a fine.
I think it might be the case that the neighbouring counties look after each other.
Anyway seeing as it's only idle curiosity, what have you to worry about?