Got my new gti recently and have started to realise quite a loud grinding/moaning noise when braking or coming off the brakes at low speeds (e.g. when reversing or slowly moving forward (parking))

What could this be? should i get it looked at?

Also the car keeps telling me to Service Now when i turn it on however the dealer (AHG) said they had serviced it before selling and done 100 point check etc...

apart from this, I am loving my new car