When a dog growls it is its way of communicating that it is uncomfortable, afraid or stressed. Dogs have a communication hierarchy that starts with subtle face shifts, lip licks and yawns. The growl is present when previous communication has failed and the dog needs to escalate its message.
Please do not think or feel “rest assured” that your dog will not bite. If it feels threatened and scared and previous other warning messages have not been heeded or ignored, then a dog's behavior may/will escalate to a snap or a bite. Our four legged family members cannot ask for a family meeting, initiate an intervention or write to their Congressman. This is how dogs communicate, through vocal gestures and physical movements.
If your dog growls, snaps or shows any behavior that indicates fear or discomfort then please consult a qualified professional positive-reinforcement dog trainer or behavior consultant to help you and your dog understand what is triggering the fear so it can be resolved, helping everyone co-exist comfortably together. After all is that not what families are all about?
Under no circumstances should you punish your dog for growling, this is equivalent to turning off your burglar alarm system and then being surprised to arrive home and find your valuables missing.