We recently had a new patio put in my backyard. About 2 to 3 days later hairline cracks started appearing some running from the front of the area to the back. When I mentioned it to my contractor he said that on his second trip to finish the job he also noticed the cracks. Since he is the landscaper for my backyard project he consulted with his concrete person and was told that he was probably given a "hot load of concrete", and that the concrete stayed in the mixer too long. My contractor is willing to do whatever needed to fix the job. But my question is what are my options? We were going to put flagstone over the concrete at a later point, so the contractor suggested that we could get it done sooner and he would give us a better price to have it done now, rather than next year. He is also willing to take up the whole thing if need be. I don't really want to go through putting a whole batch of concrete down again, but I also don't want the cracked concrete under the flagstone to haunt me later down the road. Is it okay to put the flagstone over the concrete or should we go with doing it over again?