Hello! Within 3 week of using our new bathroom and shower I am noticing mold on the shower floor. This concerns me as the fan is always on while we shower and the room gets lots of direct sunlight. There was also an issue when the tiles were first laid. They had to be ripped up because the thinset didn't actually work. Our GC said it was a bad batch of thinset. I'm beginning to suspect the shower pan may not be water tight. Any thoughts would be appreciated!