Chiming noise when toilet flushed

When we flush a Kohler toilet at my Mom's house, it makes a chiming noise like a mellow doorbell. It's not unpleasant, but odd. We're worried that it might be something we should care about and get fixed.

Does anyone know? Thanks very much.

Sorry but I have never run into a chiming toilet so I am at a loss...but I will be reading to see the answer...you could replace the fill valve and flapper and see if it changes the pitch of the chime...