Smooth flying overseas to AMS on DL, seat belt sign never goes off. FA's are busily running around taking care of business. There is no turbulence. Finally, I can hold it no longer and ask the FA if the there might come a time when the sign is turned off. She looks up at the signs, surprised, and asks me to hold on a minute. While she's gone, seat belt sign is turned off. She comes back and apologizes. The pilot just forgot. Sometimes a cigar is just a cigar.