I've read through many of the q&a's here on the board and had already presumed my issue was a worn flapper. I ordered the replacement flapper from American Standard, adjusted as per their instructions (float placement), adjusted the chain so that there is some slack when the flapper is closed and figured I was all set. Well, not so.
The toilet is almost exactly 11 years old and this issue is a recent occurrence.
I put some beet juice in the tank (I didn't have food dye) and let it sit for half an hour. There was some tinging in the bowl. There is no sign of leakage on the outside of the tank whatsoever. I removed the new flapper, cleaned off the seat where the flapper sits and reinstalled. The issue remains.
Any help or suggestions would be greatly appreciated.