Weird, does the tile feel damp or soft at all?
If it dries out as per your prediction you could try sealing with sealguard. This will provide a water resistant coating that does not change the appearance of the tile surface. IMO it's great for ceramics, porcelain and grout but rubbish for natural stone.
Make sure that the tile is securely fixed beforehand though, there's no point in sealing a tile that can potentially fall off the wall.
