This is the email I recieved from LFAT
Dear Sir,
You landed at 17h40 UTC. Sunset was at 17h16 UTC. All the flights have
been considered as day-flights until 17h46 UTC.
Certainly, you arrived at the reception desk after 17h46 UTC so that they
considered your flight as a night flight using the lighting.
Nevertheless, I have decided to offer you 2 free landing fees.
Please let me know an adress where I can send the 2 free landing fees.
Looking forward to hearing from you,
Best regards
Jean Jacques FROMENTIN
I guess that is fairly reasonable.