I have layed two ceramic floors in two kitchens (each about 300 sq. ft.)recent 2 yrs and other nearly 6 yrs ago. The oldest has never had a tile crack or any evidence of a problem. The most recent has one tile that one can feel a little flex under - although grout has not cracked or tile cracked. The potential home buyers are concerned that the floor will not remain attached. These are both linoleum over hardwood. If there is a significant problem would it have already presented itself given the time and traffic? What is your advise? Thanks.