We got new tile 5 months ago and whenever I wipe the grout, the color rubs off on the cloth.The contractor says the grout is sufficiently hard and seems to want me to accept this as normal, since the grout color isn't usually spreading over the whole floor. We have already tried sealing and it didn't help. We haven't had use of these rooms for months because of this.The grout is Mapei Ultraplus FA. Is this normal? Is the only option to regrout?