It's a quite frustrating system with DSG. When the car comes to a stop, the engine stops. When you release the brake, it starts again. However, if you are stationary in a line of traffic, it means having to keep your foot on the brake to make sure the engine stays off, so the driver behind has to stare at your brake lights. Us courteous drivers who consider the car behind would normally come off the brake and let the Auto Hold, hold the car, but doing that will start the engine again.
Also when manoeuvring, it can stop the engine when you are stationary, going between D and R. It will re-start instantly when you release the brake, but it can make you look as if you've stalled the car.
You can of course switch it off, or trick it by applying slightly less brake pedal pressure to bring the car to a stop, but there is a very fine line between how much pressure to apply for the engine to turn off or not. You really have to think about it, which kind off goes against the rest of the cars effort saving driver aids.