Unfortunately, that's not true. She needs to continue to be socialized, so that she remains friendly and does not become timid or fearful of unfamiliar situations. Dogs can change a lot as they grow up from puppyhood to adulthood, and socialization is an ongoing process. It sounds like you are off to a good start though, and the fact that she has a good personality now definitely gives you something to work with.
Just as another example of what can happen as a result of not socializing though...I have a friend whose parents have 3 Miniature Pinschers. The parents owned all 3 dogs since they were puppies, and they started out as friendly tail wagging babies who would greet visitors and enjoyed attention. Now, however, as adults they have become the most vicious little dogs I have ever seen. I think a lot of it is fear aggression, and the fact that the owners haven't established a clear leadership, so the dogs are taking over that role. The owners did not make much effort to socialize their dogs, or to train them. The dogs actually attack anyone who visits, jumping and snarling and biting pant legs, and I think they've even bite for real sometimes. If they don't yet, I'm sure they will soon. They don't let people get more than a few feet inside of the door, and don't let anyone near "their" couch or "their" human, etc. I think you get the picture, and I'm sure part of it is that with three of them, they form a pack and more aggressive than one would probably be individually.
Anyway, just keep socializing, and I'm sure your dog will turn out great. You're obviously a much more responsible owner than my example.