I have been impressed that my 8 month old puppy hasn't been much of a barker. But over the last few days, he is barking at every little noise that he hears. He used to be able to sit at the front door and watch people and other dogs walk by without a peep. Now he barks like crazy and wants to go outside and chase them. Even when we take walks now, he starts barking at people even without dogs - he never used to do this before. Does anyone know why this would have started out of nowhere? He did experience his first snow over the weekend, could that have anything to do with it?