My 6 month-old labrador, Misty, displayed some disturbing behaviour to me and my partner when we were out walking her the other day. She was off the leash in a park, and as we walked towards the golf course a man came out of nowhere with some clubs and Misty went crazy! She was jumping, barking and growling, and the hairs on the back of her neck were up. We restrained her but I was completely shocked afterwards. Misty has never done this before and I put in extra effort to socialise her from the day we got her - she has met nearly everyone in the community and normally wags her tail and gets excited when she sees other people! Does anyone know why she would have lunged at this man? I am very confused, I love her dearly and I dont want her to become an aggressive, biting dog.