Our downstairs shower head runs when running water in other rooms.
Specifics: Kohler single handle. Leak increases to steady stream as water flow increases in other rooms. No leak or drips otherwise. With no other rooms running water the valve seems to function without issue.
Installed in January 2008. Very rarely used (couple times per year). Noticed leak in 2009. Have recently finished rest of the basement and now want to stop this issue.