How about an update?
I'm been doing some reading about rottweilers and it amazing how many subtle signs there can be that people miss that could warn of potentially dangerous situation. The sad part is that many people, and I'm not judging the owner of the dog that encountered, don't recognize the signs of dominance. I'm sure it can be important with all breeds, but with large dogs it becomes more important. Below are a couple of examples of indications that you dog doesn't look at you as the "boss" or pack leader.
(1) If your dog run in and out doors before you, or without your specific permission. - We are working with Rufus so that he sits at the door and gate until we give a verbal ok.
(2) If you dog is protective of its food, toys or treats. - We are careful about controlling these items and removing them if necessary.
I was just reading this morning that growling is a sign that the dog is uncomfortable with the current situation in some way (thank you captain obvious), but rotts can even give the same signal when they are looking back (eyes darting) and forth between something and their owner. It's difficult to explain which is why it would be easy to miss. There was a couple of really subtle signs that I have never heard of that I can't remember right now.
I actually got Rufus to sit and lay down with hand signals while I was sitting on the living room couch and he was watching me from the back deck looking through the sliding glass door. He was a good 25 feet away! We didn't realize that he understood the signals that well.