Pazu, the past few days, has been having trouble with his head being pet. I'm not sure if it has anything to do with some bumps on the back of his neck/bottom half of his head. He sees a person, gets excited, heads over to the person, and sits down.. as if asking to get pet. This has never been a problem before. The person then reaches down and starts petting his head. The first few seconds are okay... maybe 10-15 seconds. Then the person is looking at me and talking.. and then midway through, I see Pazu's lip pursuing.. his ears flattening out... and at that point, I'll tell the person - please remove your hand NOW! ... Just as Pazu whips around and nips/misses the hand that was just petting him. No bleeding, but his teeth definitely touch the skin. Then he comes running to me.
I am truly baffled by this behavior.
When you say he has bumps on his head - are these a new development? Does he show any discomfort when handled near the area? Has he ever bit you when you give him head pets, or is it strictly towards strangers?
Yes the bumps are a new development. We had a conflict with a foster dog and I think it's possible that he might be a little bruised on his neck/head area. It seems to have scabbed over so it doesn't appear like he's uncomfortable or hurting.
No he doesn't bite me when I give him head pets, but also in the past two days, I give him head pets with treats, so he's been pretty focused on the food. If I let my hand linger too long, he appears to get uncomfortable. I watch his muzzle more than strangers do.
Strangers (my friends) are more commonly getting nipped because they are confused by his behavior. A friendly dog coming up to you voluntarily and sitting down in front of you... and then he's fine for the first few pets.. and then his behavior changes. I've had to tell people not to pet him, but of course some people do it anyway.
I echo Jennifer's sentiments below. He may be a little tender up there. Sudden aversion to being touched in a localized area of the body usually points to discomfort/pain emanating from it.
I think it's due to pain. He may have an abcess or infection developing- I'd take him to the vet to be checked out.
I second Jennifer's advice. Those spots could be getting infected and very sore. A trip to the vet seems to be in order.