OK folks, I learned a lot by reading your posts regarding to what happened on my friends flight and I thank you for this even if it was a little bit hard to understand everything. I phoned him back yesterday evening (I'm on GMT+1) to know if he was really meaning the flaps and it is so. He told me that it was so unusual that the f/as get very surprised (and so the trolley that made a trip trough the cabin
). He noticed them extended on the wings (a little less than half way and the plane slowed down so the engines sound) and saw them retracted after a couple of minutes. Immediately after retraction, the plane recovered it's normal cruising and engine sound that it is used to hear. That's all I have for you.