There is a saying in the construction and building industry: “Concrete is guaranteed to do three things; Get hard, turn gray, and crack”. Cracking is very common, expected, and is normal for concrete. Since all cementitious products crack, and such cracking can only be minimized or controlled to a degree, neither concrete slabs or flatwork are warranted against all cracking. Slabs are designed to move at expansion and contraction joints. Subsequently the floor slab maintenance (both interior and exterior) is a homeowner responsibility.
NOTE that improper care and maintenance of concrete will void the Homebuilders Limited warranty. For more information please see your HBLW (Home Builder Limited Warranty).