I recently had my bathroom floor tiled and there is a problem with the grout. The floor was tiled completely and left to dry for 48 hours. When the tile guy grouted, he used TEC XT grout in the color grey. After the grout dried, we noticed there were several dark grey and black discolorations on a good portion of the grouted areas. I would say 20% of the "grey" grout is either dark grey or black, and it is clearly an eyesore. My question is, what happened, did we get a bad bag of grout or was there an instal error (ie too much water in mix or to quick in clean-up) and how to best correct. Do you think we should just rip out all the grout and re-do.