Stamping concrete is a process of stretching the surface of the hardening concrete to create a unique indented pattern/texture on an otherwise flat surface. Because stamps impose significant stress on the surface, surface cracking often occurs. In order to resolve this problem keep a small bucket of water and a 3- to 7-inch (paint) roller with 1/2-inch nap on-hand. Then, whenever these small cracks appear while stamping, take your wet roller and carefully moisten the crack with your roller. This relieves the surface tension (stress) and fixes the crack.
— Steve VandeWater, Noblesville, IN