Izaak has been so good for the past couple of months. He follows me everywhere, and never seems to want to do those naughty puppy things anymore. Well that was until yesterday. While doing my laundry, he totally shredded the pile of towel I had on the floor waiting to be washed. Then when I crated him to run out, he shredded his pillow. Where did this come from, and is it normal behavior at 19 months?