Leaking Toilet??

DH installed a toilet on a tile floor in our new house. I didn't notice anything for right away but now it seems that one of the grout lines that goes under where the toliet meets the floor is always wet, just one even though there are 4 coming out from the base. Not a lot just about an inch past the base of the toilet. I looked in the basement under and didn't notice any water stains, but something has to making the grout line look wet, right? The flange thingy is screwed directly to the subfloor and then we have the CBU & tile. We put 2 wax rings under cause it didn't look like one was getting a very good seal......Is there anything that can be done?? More importantly do you know what we did wrong as we are going to install another toilet in the next week or two and eventually two more after that using the same installation practices.

Thanks so much. I'd attach pictures but I left my camera at our friend's house two hours away.

Can you rock the toilet? If so, reset it with new wax rings AND shims. A rocking toilet will break the wax seal. The stuff squishes down to make the seal, but if it later rocks, it doesn't rebound, and you have a crack in the seal. Essentially, it's a two-step process: set the toilet without wax, determine where to shim, then remove, install with wax and shims while only pushing straight down.

Moisture could be from that, or a crack or defect in the toilet, or condensation. It could also be from water dribbling down from the tank to bowl connection, or from people (men or boys or pets) missing.