........You should be able to do just about anything to your dog and not have to worry about getting a bite in the face that requires stitches. You should certainly be able to touch him anywhere. The face, stomach, his behind, his tail, anywhere. Anyone in your family should be able to do this, Mom, Dad, and all kids regardless of age. Certainly giving him a hug should not be a reason for a bite in the face. The exception here would be in the case of an injury that caused the dog some pain, in that case he might just react.
What do you do at the vet when you have to lift him up on the table, put a hockey mask on before lifting him because he might bite you in the face? Maybe you would say he would not ever bite you, and maybe that's the fact. If that's the case then you know what the problem is, your dog does not respect your son the same as he respects you. Good news is you can fix that one.
Don't kid yourself, we too often excuse our dogs behavior because we think he didn't like what you were doing to him. Beating him with a stick is one thing, but picking him up is another. What's next, he bites your son because he picks up your dogs chew toy, because he just didn't like your son to pick it up?
It's hard to really know what is going on with your dog by just reading a post. If it were me I would error on the side of caution and not leave him unsupervised with the kids. Maybe get a professional to help, try to understand why this happened so you can fix it before it happens again. Have him checked by a vet to make sure there are no health issues.
