Agression in young German Shepard

Question
Labman;   i have a 4 year old black shepard I have had since a pup...He came over from France, I also have a 7-year old Belgian Malanios---both male...the malanios is protection trained as well as the shepard...they have gotten  along well until recently the shepard has been showing his teeth when he is told to do a command he doesnt want to do. This I overlooked because he completed his command without hesitation. The shepard is my daughters dog and the two are/were inseperable, she handles both dogs well. Two nights ago she and the shepard were on the couch as usual his head in her lap...he all of a sudden nipped her in the face and then turned on my wife and nipped her on the arm.
I came on the seen after and removed him and put him in his kennel...reviewed the situation and decided to keep a close eye out for any other actions that were not consistant. Two days later my son and I were playing pool in the garage and he was "at place", he sat up and I reached down to hug him and he lashed out and bit my ear,,,I immediatly put him in his kennel. These actions I feel are very uncharacteristic of this dog, I had the Malanios "try me" and I immediatly cured that and have had no real problems since....but the temperment of both dogs are so different I have had a difficult time finding how to remedy the problem...The malanios is so strong and i could overpower him. but the shepard is so different I do not want to break is spirit.

Answer
Once a dog is past 3, usually they are not a likely to challenge pack order.  I am having a hard time figuring out what may be happening here.  If a vet check doesn't turn up anything, you may need to consult a dog behaviorist.  I am afraid I can't help you find a good one.