how to tell if flange leaks?
I had a new tile floor and toilet installed in my bathroom about 6 months ago. A couple of months later, I noticed that some of the grout near the toilet is darker than the lines around them, and I was wondering if maybe the toilet is leaking at the flange, below the tile but above the waterproofing on the subfloor. It is a small hex tile, so there are lots of grout lines, and there are maybe 6 or 7 darker lines between 4 or 5 tiles. They are near one part of the toilet, but don't run under the toilet, and don't seem to be spreading over the past couple of months since I noticed them.
I didn't put caulk at the back of the toilet and don't see anything leaking there. I've looked at the floor underneath (I have access from the basement) and don't see any water, but the tile guy put a water barrier under the mortar base, so it may not be leaking down through that. The toilet doesn't run, so it doesn't seem like the bowl is draining, even slowly.
Is there any way to see if the toilet is leaking without taking the whole thing off and putting in a new wax ring? If I do take the toilet off, how will I know if it has been leaking? If it's not coming through to the subfloor, should I just leave it?