Mine did the same thing recently while the wife was driving it. Of course she totally freaked out and drove it immediatly to my independent. I got a call at work from him explaining that my wife was there with the car and that he had driven it approximately 20 miles trying to duplicate the condition (with my wife in the passenger's seat) but it did not duplicate. He explained that there is nothing to worry about unless it repeately does it or is accompanied by other problems (ie rough idle, ck engine light, missing, etc) and explained that although a MB is as close to prefection as one can get in an automobile (He loves his Benzes), they do "glitch" on rare occasions.
Hope this helps