Parrots who really trust their owner will sometimes lay on their back on the owners lap which is a birds most venerable position. Likewise dogs who put your hand in their mouth without biting can be a great show of respect from a dog, it can also be playing or a combination of the two. A pit and a fila pup playing can really knock some things around, keep all fragile stuff put up high right? I'll bet your fila grabs the pit by the neck and gets dragged around, no fun with sharp puppy teeth LOL. Fila pups never tire of that. I sent you a PM.