Is it an Air France flight operated by Air France or a KLM flight operated by KLM? Then it is definitely an issue in case the flight is not already oversold.
If you have booked a codeshare with AF flight number or KL flight number - but the flight operated by another airline (e.g. Etihad, AeroMexico, etc.) you won't be able to see the seatmap. You could only call the hotline and let them have a look.