We moved into our house about a year ago. One of the tiles next to the drain was loose. I stepped on the drain and it moved a tiny bit and got caught under some other tile; the loose tile popped off. The drain was a tiny bit off level but now much. No problems with drainage. In my efforts to straighten the drain, I realized I could screw it off, so I did. The mortar base, at least around the drain itself, is not hard. It's like packed sand. Is this normal? I get the impression this isn't normal. Do we have a problem? Is it a big problem? Please tell me I don't have to rip up my whole shower.