an occassional snap of temper is nothing to be too shocked over, at least I never have given it a second thought. They are dogs, dogs bite. That's one of the first lessons I learned as a kid.
Now if it starts to become a pattern or a trend, then that's when I start to become concerned.
Heck, even my black lab who I have now, and have had for going on 13 years now, has drawn blood on me on occassion. But I have always looked back on the incidents and thought to myself, "boy that was dumb to have my (face/hand/etc.) that close to his mouth when he was all wound up and aggitated. I've never worried about wether I could trust him, or if I had to re-home him. You just have to be confident with dogs, they can pick up on people who aren't confident, and if you can't be confident, then FAKE IT!
I've learned how to read Sams emotions and expressions much better since then, and I know when he's getting ready to really loose his temper, and I have learned what can difuse him. Fortunately he's generally a pretty mellow tempered dog.
Glad to hear that things are settling down with Oso.
Outside of a dog, a book is man's best friend. Inside of a dog, it's too dark to read. Groucho Marx