Just because an aggressive dog has made improvements at a training program doesn’t mean that the aggression is completely gone. Its mindset and feelings towards a variety of situations have definitely changed. Remember that aggression can still come back without the owner’s constant awareness of every new situation.
When you are living with a dog who is aggressive, nervous, anxious, fearful etc you need to pay attention at all times at your dog's behaviour. There is no way for one training program to prepare the dog for absolutely every situation that life presents.
It is rare that a dog is COMPLETELY rehabilitated. This is why it is so important to continue training and understanding your dog’s triggers and thresholds to every new scenario.
Every new successful moment with your dog is another step towards a dog who is closer being complete.