Thats what i noticed too Knny...he has a sad way of looking out of his eyes...
Vet...you should try and find out what happened to this dog.
You never know what could trigger him. I'm not saying he's a bad dog but safety wise it is not a bad idea to check his likes and dislikes .
Oh, I put him through the paces before I ever brought him home and I've watched things closely. I've got two female pits in my house and at the time I had my old border collie, I don't need a dog fight and this dog is nearly the size of my wife. I don't need something bad to happen, although the last mistake he would make would be to bite my wife....she'd put a stop to that.

Its a matter of me learning his personality and his learning mine and my wife's.
As far as a personality evaluation goes, my wife and I both evaluated him independantly of each other---he's one of the most stable dogs I've ever encountered as a rescue, especially as an intact male. Right now he's asleep at my feet, drooling on my right big toe. He does show some sexual interest in the neighbors intact female corgi (Now that'd be a mix) but he's otherwise not overly horny, which means he doesn't have some of the stupid intact male dog personality traits. He's pissed in the house all of 3 times and crapped twice (once in his kennel), so house training is good.
What is weird is it almost seemed as if he didn't know how to play like a dog---the puppy is working hard to fix that problem---I swear that dog is like a hummingbird on speed right now, I have to get her on a treadmill to burn off some of her excess energy. Now I've got to give them scheduled time outs to keep them from tearing my house apart. We are still learning fetch. He now realizes that he can chase the ball (I think). The last time I threw it down the hall, he gave me a look like, "well stupid, you threw it, you go get it" and layed down. I won't let him go near the rope or the tree the puppy uses because of his size and knees. I don't want him to blow out a knee.
Training has been going well, but its a bit slow, some of which is my fault because I've been busy with work. Sit, shake, come, STOP and NO are all firmly cemented. We are working on down. There's some sort of a disconnect between asking him to do something and him doing it--my wife says he's a bit dumb, I think he's trying to figure out whats going to happen. He doesn't do anything without first looking at it, which I'm sure is a product of his background.
Overall, I like this dog. He's a good dog.