We have 3 kitchen tiles that have developed a diagonal hairline crack. My husband said it's because the slab is cracking and the tile is glued down tight enough so it is following the slab crack. Is there any way of filling the hairline crack, or do the tiles have to be removed, replaced, and the slab crack filled?

If you don't mind the crack in the tiles, you could always caulk the crack with a siliconized latex caulk from one of the grout companies that matches as close as possible to the color of the tile, but I'd prefer to remove the tiles, as well as a few tiles on either side, put down a crack suppression membrane, and retile. One thing, first, though-- carefully rub your finger across the crack. Are both sides the same height, or is one side higher than the other?