2002 S500 Transmission Delay

[cuvees]

I bought a 2002 S500 with about 14k miles two months ago. I recently noticed that when I shift from N to D, there is a delay of about 2 seconds until the transmission engages. I also noticed that after driving the car for more than 10 miles (i.e. the transmission is hot) and shift from D back to N, the transmission makes a "tooug" sound as if a disc has disengaged. I am not sure if this was a pre-exisisting condition when I bought the car. Any ideas on what is going on with the transmission. Since this car has an electronic transmission and is complicated in general, should I be concerned? The car is still under warranty.