I bought the toilet a month ago; had it installed by a pro. There's a slow drip from the tank bottom. I checked the tank inside around the bolt holes for irregularities, and there're none.
I noticed when unboxing the toilet that that the O-ring tank seal is mad of a spongy, open-celled foam. When I shine a flashlight between the tank and bowl I see beads of water on the ring. I suspect it is passing water slowly through itself.
I contacted Toto and they are sending a new ring, but I doubt it will fix the problem if it's of the same material.
Comments, suggestions appreciated.