Two year old house and between 8-24 months, a few crack lines show up in some area. There are 3, two of which are no thicker than two nickels but one is about a quarter of an inch. They're not long, end at corners or edge of the window frame. The builder won't fix it because it's normal they say and I've noticed that other houses with stucco have them too. It's my first home so I'm new to this and to house with stucco cover. Do I need to be concern?