Hi I have an 11 year old Black lab Weimaraner mix. Let me give you a little information about what is presently going on. She has been a great dog for 11 years. She grew up in my parents house with my 2 sisters, my brother, myself and my now husband ( he has been with her for 4 years). My parents have decided to move to Florida my 2 sisters moved there 2 years ago. I just recently got married and we bought a house. So my parent decided that it would be a bit easier for the dog to move to our house which is only and hour from where they live now as aposed to a 25 hour move to Florida. Not to mention My dog Cynders has kind of attached herself to my husband and I. But We have been in the new house now for 3 months. When she first got there it was a bit odd for her. She didn't have a fenced in yard at my parents and she was a leashed dog when she went anywhere. Now we can let her out in the yard anytime with no leash because we are fenced in. She adjusted to that very well. She went from a senior dog activity level to a puppy which was great for us. We love being outside. But just recently she has started to act a bit odd. She is hidding in our closet all the time. She usually did it during storm which I know is a bit more normal. But now she is doing it all the time even when there are no storms. Now here is the big problem. We just had a friend over this weekend.Whom spent the night at our house. The dog was great with her all night on Saturday and on Sunday morning until she came into our room and sat down on the bed with my husband and I one the bed. The dog nugged me to come up. Which isn't unusal. I let her up on the bed. The dog was laying on her belly between my husband and I and my friend was sitting on the foot of the bed petting her head. My friend lened over to give the dog a kiss on the top of the head(which she had done several times befor) and the dog grabbed her lower lip. No growle just a quick bite with a yappy bark to it. I immediately grabed her musel and yelled at her telling her no. Then placed her in the bathroom with the door closed. I then went to check on my freind. The dog did grab her lip No serious injury put a small little puncture wound on the inside of the lip and on the out. My friend wasn't really bleeding but her lip did get really swallon. She was really great about it. I apologized till I was blue in the face. She said that it wasn't the dogs fault she was just protecting us. But this is the first time the dog has ever done anything like that before and she is 11 years old. She is very aggresive to other dogs so we don't let her around them but never toward a human. I am a bit nervious of having friends over to the house now. Can anyone help with and explination? (Sorry I am really bad at spelling)