Magic moment

This series is beautiful from start to finish. Within a minute I was drawn into the movie. It has a documentary feel to it, but in a way you believe and care for the characters. The colours, the pictures and the music, all seamed to melt together perfectly.
One of my favourite scenes is in the first episode. Monet, Bazille and Renoir in the Fontainebleau forest. They start to paint, and for a second, Renoir is whistling in tune with the melody, or so it seems. I thought that was truly a magic moment! For a moment I felt I was with them as an invisible voyeur.

Did someone else noticed the whistling, or is it my imagination and let the makers us believe that he was?