[tosha_e_1]

Hello,
We have recently adopted a 3 year old male yorkie. He is not neutered. He is a very good dog. He loves to snuggle and play fetch with the kids. He sleeps with my daughter (12 years old). He loves to tag a long for car rides and go for walks.
But I am noticing an alarming behavior and wondering if I can get some advice on it? We have 4 kids. Ages 12, 7, 5 and 1. Parker (the yorkie) came from a home also with 4 kids.... all under the age of 5. I am told he is great with kids and has never had any problems. We visited with Parker for a long time before we decided he would be a good fit for our family. He is our only pet. I even took him to a park where there were many people to see how he would react to strangers and kids coming up to him. My kids crawled around with him and played with him for a great while. We have only had him 3 nights. He has been great. This afternoon though, while my 1 year old was pulling himself up near me on the couch, Parker SNAPPED at him!! He hasn't done ANY of that before with us. My 1 year old doesn't even typically pay any attention to him. He may pet him while he sits in my lap. And I work on gentle touch and hold his hand to teach him etc. He has never hit him or even pulled at his ears. In fact, a few times he has sat next to Parker while he was eating and Parker has been content. He has never shown any signs of stress.
Any idea as to WHY this sudden change? How worried should I be? We all love Parker, and I don't want to rehome him. Are there training methods that can help? What can we do in the meantime? I was considering verbally scolding him and sending him to his bed (crate) for a while. Then maybe having my one year old sit with me during treats time, and my 1 year old gently give him the treats. (unless of course Parker looks stressed) Thoughts?