I purchased a GSD named Sarah about 5 months ago and now she is 9 months old. We took her to training at PetSmart and she did awesome. But for about the past month and a half she has been pretty nippy. It happens mainly towards my brother, out of nowhere she will just go up to him and start nipping on his clothing and start to grunt. Sometimes she will do it to both of my parents also but rarely to me. I have tried to do the yelp thing, a water bottle and the get up and ignore her technique but she just gets up and follows you pulls on your pants. Shes not being aggressive it just seems like she thinks she is playing. Does anyone have any other suggestions for me? Thank you!