Our little girl is a lab/golden retriever mix. She is sweet as can be, most of the time. Lately she has moments where she gets aggressive. Bites too hard, snarls, lunches and growls. It happens randomly when I sit down, she will come sit on my lap and be all sweet and then suddenly start biting me. I yelp and get up and walk away, give it a few minutes and then sit back down and she will do it again. She will sometimes hug my leg and try to bite my leg when I am walking. She isn't food aggressive, I can feed her out of my hand just fine. I've tried laying her down on her side until she gives and after I let her go she will lunge again. She has plenty of toys, we have her on a feeding/potty schedule, I am home ALL DAY with her and she goes outside two to three times a day for running and playing. She does great in her crate. She is learning basic commands really well! Already knows sit and down. What am I doing wrong?