My entire bathroom is covered in this black tile from previous owners, on 3 walls and shower surround. Upon having to clean it myself, I noticed all of the tile is covered in these hairline cracks. You can't see them from afar but you can feel them if you press your finger against them. Our original plan was to reglaze. Is it ok to reglaze tile that looks like this? Do you think the cracking is from movement since the entire bathroom is the same way?