My husband and I recently adopted a rescue dog, it will be about a month. The vet says she is between 3-5 years old. She is fairly comfortable with my husband and I, likes to be pet and played with. Never growls at us. However, when someone comes over our house she will sometimes let out a low growl. If left alone she gets over it and eventually warms up on her own time. Usually when taking her out for a walk she can be nervous when walking past someone or a bike but can move on rather quickly. When another dog is walking she will sometimes want to check it out but can move on quickly. Today I took her out for a walk and at the end of our walk a larger dog was in front of us that she had not seen before, she started growling and lunging at the dog. After a second I was able to get her attention and go home. But I am nervous about this. Am I overreacting? This is my first dog.