Hi! I have a 1 and 1/2 year old blue heeler. She is very sweet to most people, but sometimes when new people come into my house, she will try to nip at their hands and if they sit down, she will sit either right next to them or under them constantly watching them. She’s never actually bitten anybody, and when she does nip it’s not a hard bite, but it does scare some people. She started this a few months ago. She has never been aggressive towards anyone or bitten anyone. I’m not sure if she is trying to protect me or the house or something because she has done it in one other place besides my house. If anyone has any tips please help! Thanks in advance ?