I recently noticed a 6 inch L shaped area of discoloration on the ceiling in my kitchen. The ceiling was slightly damp and soft and it's directly above the corner of my shower stall, so we called the plumber to look at it. He said that the small amount of water that gets on the floor when someone gets out of the shower could be seeping through the grout and the ceiling below. Is this possible? The previous owner put in the tile floor and shower (he owns a floor/tile co) and said that the tile was sealed. Is this a logical explanation or do I need to get the opinion of another plumber?