RS5 subtle clicking
 

Not the ABS clicking when you reach 25 mph if that's what yall are thinking. But after i switch to manual shifting by moving the gear selector to the right and then switch back to normal automatic mode, i hear a click every single time i put minimal pressure on the gas pedal. The first millimeter of gas pedal depression, very subtle click like a gear moving into place or something. Don't hear it during normal start up and normal driving when first starting the car under the automatic shifting and drive around for a whole 45 minutes and still nothing if i never switch to the manual shifting mode. Only happens after I shift it into manual, and then come back to automatic does that soft click sounds happen. Just really strange, anyone else experience this?

More specifically, the soft click sound is best appreciated at low speeds where road noise is minimal. Can elicit it when accelerating slowly, then taking foot off gas pedal so that car is just beginning to slow down a little, and then press down on gas pedal again. Right as soon as you depress the gas pedal, you hear that soft click.
Don't know if it's a relay sound or something else. Car is staying in same gear.
But if I let go of the gas pedal and the car is still accelerating (not slowing down), then I dont hear that click if i press on the gas pedal a second time.