I picked up my 560SL and drove it 1650 miles home, it didn't miss a beat, fantastic!

My questions:-
The AUTOM button on the climate control system seems clear, is it supposed to light up when in use?

When traveling at 75 using the cruse control system the car runs very smooth, if I touch the brake (to pause the cruse system) I notice a slight clunk by my feet as the cruse disengages the throttle. Any ideas of what to check or is this normal?

The vehicle is very clean, low mileage (32k) and doesn't have any squeaks or rattles. The clunk noise doesn't happen when I use the throttle to get the vehicle to 75, hold the speed and then let off the gas.

I would appreciate your thoughts.