AGGRESSION TOWARD PEOPLE!
I HAVE A 3 YR OLD Rott, and i take him with me in the car and to parades,etc. He has never been aggressive before and has always been real nice.
I had taken him to petsmart and he was getting petted and getting treats, and seemed very happy. After that we went to petco and he was fine until a worker had came up to him. At first he licked her hand, but the she proceeded to kneel down in front of his face and was rubbing his ears all around, he started growling, she would not stop touching him, then he snapped at her and got her hand in his mouth. I opened his mouth to remove her hand. Afterward he seemed really stressed.The lady worker had just been in a accident, had black around eyes and was cut up pretty bad, all over her face n arms and hands.My dog did not bite hard enough to puncture skin, so she said it was ok. But it's not.
It scared me cause he's never done such a thing, and now i can't trust him to take him out with me. What if that had been a child!!!
My question is "where do i go from here?" Do i not take him with me or should i take him with me but wearing a muzzle?
I can understand why you are so upset and can see that you're confidence in your dog is badly shaken, however I think perhaps you are panicking a little and may be over-reacting to a 'one off' situation.
Obviously what happened is a big 'NO-NO' and it's never okay for a dog of any kind, let alone a Rottweiler or other big, guardian breed with an undeservedly bad reputation, to snap or bite, and you're absolutely right to be upset and concerned. However, from what you say this is a one-off incident in a dog who has up until now been unfailingly good-tempered and is basically a very sound animal. There seem to me that your dog was put in a position where he was very uncomfortable and felt threatened, and he reacted by 'warning' the person who was making him feel that way.
He gave warning by growling, and when that wasn't heeded, he snapped at the girl but he didn't bite hard or break the skin and allowed you to open his mouth and let her go. That isn't a dog with intent to injure, or one that is indiscriminately aggressive in my opinion.
You know your dog better than anyone, and unless you feel that his personality overall has changed in some way, or that he is showing signs of being aggressive in other situations or in general towards people, then I wouldn't over-react here. I doubt he needs a muzzle, and I certainly wouldn't advise that you stop taking him out with you, the best thing you can do now is to learn from this experience and take steps to make sure it never happens again.
Your dog is relying on you to protect him and to keep him safe in certain situations, so if you see someone doing something that is making him uncomfortable (and now you know what seemed to trigger his reaction you can avoid allowing people to do the same thing), simply tell them that he doesn't really like that and ask them to stop. Show them what he DOES like in terms of petting and always have treats with you so that you can give people treats to feed him instead. Socialization is very important for Rotties and it's important that you continue to give him a chance to be around other people, dogs and places. It's also important that you take the leading role and take action if you feel someone is stepping over the line with your dog.... that way he won't have to!
Also, bear in mind that dogs are very intuitive and pick up on their owners emotions and body language very quickly. It's important that you not feel or act nervous or afraid when you are out with him, if he feels that from you he will interpret it as being in a situation where you and he are threatened and he will become defensive and worried too. Try to remember that he's the same dog you've always taken out with you, and that he's not now a 'bad' or 'vicious' dog, simply one that was overstimulated and didn't know how else to put an end to it.
Of course, if he EVER does this again, or he starts to show other signs of aggression in public or at home, then you should talk to your vet or a dog trainer or behavioral specialist and ask for some advice on reshaping his behavior and reactions. I don't take aggression in a dog of any kind lightly, and I'm not advocating that people allow unsocialized, aggressive or nippy dogs to snap at people! It just seems to me that this was an isolated incident in a dog who is otherwise very even-tempered and well-behaved and because he's a big dog, and perhaps even because he's a Rottweiler, there's an element of overreaction, which is understandable but unnecessary.
I hope this helps and puts your mind at rest somewhat. I wish you the very best of luck with your dog.