Even though an engineer designed the foundation and the builder constructed it according to engineering requirments, surface cracks can still develop in the wall and on the floor. Cracks are not detrimental to the structural integrity of the house. Also shrinkage or backfill cracks are very usual in foundation wall and basement floor, especially at the corners of basement windows. If a crack develops in a foundation wall that allow water to come through, you need to fix the crack, otherwise you don't need to do anything.