Great question! This noise is a part of the spritzing process, and there is nothing to be alarmed about.
The noise you hear is the Aerflo system releasing the CO2 built up in the bottle by pressing the button. Typically you will push on the device in three short bursts and it will then release the air, causing the noise that you hear.
You can see this in action via our quick start video on https://aerflo.co/start