GTI brake question

For some reason, when I pressed the brake lightly just to slow the car down from going down a hill, the brake vibrates as if how it feels like when ABS is on. The weird thing is that it moves back and forth not as quickly as ABS and I was scared when it suddenly moved inward and then it moved enough that my foot moved and so as my anke and when the pedal pushed back up, my foot was kinda locked at the brake pedal as my foot was shifted and I had to totally remove my foot for the brake to bounce back in place. It is hard to describe but why is this happening and is this normal?

First of all, why are you still braking while shifting? Were you trying to heel-toe?
How many miles are on your car? Maybe it's still breaking in.

Mine were perfectly fine. The brakes felt very strong the first 150 miles. Now it's normal.

ya very touchy brakes at first!

First of all, I wasn't shifting. I was saying the sudden drop of the brake pedal shifted my foot. It has very little miles and I was just wondering there is a bubble in the brake fluid or it is something else

Yeah you gotta drive careful for the first 100 km, do not brake to hard, do not drive faster than 150 km/h etc.

It's a normal procedure for new cars in order to get them working alright.
If you do it correct, the problem should solve itself as soon as the car is "eingefahren" as we say in Germany.

Cheers,
Michael

Could be a parallelism of your brake disk is out of tolerance. Does it happen only when you brake?