Sounds right to me. Just installed tile on kitchen countertops and I am not having that problem. While allowing grout to cure one of my kids got grease on grout joint and stained it. Got degreaser and cleaned it OK. Never have the problem of grout cutting loose. We even used a brush on it trying to get the grease out before trying the degreaser. Grout did not cut down. I did have a problem with grout sticking to some of the tile on one of the countertops and can't get it off does anyone have a solution. By the way it has now cured and I am going to seal it today. Any help would be appreciated.