Did you leave the flooring in the house 2 weeks prior to installing it. This allows the flooring to be in the same conditions as the rest of the house prior to installing it. This usually takes about 2 weeks. If the flooring is damper than the house at the time of the install, when the flooring dries out to match the house a crack will form. As far as I know, the only way to correct this is to pull it up and relay it, or live with it.