I also notice this, it seems the singhs were laughing at the simran being done.
Was a group of about 5 little youngers all in bana laughing a way. A big shame i dont think they were bothered about the surti of the sangath whilst others wanted to concentrate on gurbani, they need to be approached next time or if they are reading to think twice of there action when in guru ji's darbar.
They did namsakar to guru granth sahib by walking around sri guru granth sahib and showed full respect but then wasted there time laughing away and walking in and out of the diwan, all seems to be for show.