I notice on my wife's SUV when stopped at a light or stop I feel her transmission or possibly the air suspension lower. I doubt this is normal but it seems to drive great regardless. To me it feels like the air in the rear suspension settling like when you lower it from normal to low setting.

 

It could just be the load leveling suspension working. Does it do it all the time, or just when you first start out on a drive?

 

It seems to do it after we come to a stop. When I take my foot off the brake is when I notice it. It's very subtle but noticeable.

 

You're SURE it's rear suspension related and not the driveshaft binding? Pretty common when they need grease to "thunk" as you let off the brakes after coming to a stop.