Daily Chinese Idiom Guessing Game
A sign of trouble or disturbance; a slight indication that something is happening.
风稍一吹，草就摇晃。比喻微小的变动。
《敦煌变文集·伍子胥变文》偷踪窃道，饮气吐声。风吹草动，即便藏形。”
The sudden silence in the room was a 'wind-blown grass' that made everyone uneasy.