ya, around each spark plug tube(forgot the name) there is a little gasket(looks like a ring) that goes around that tube, between the head and the valve cover. its called a spark plug grommet and its like 2-3 bucks for each. you need to remove the valve cover to replace these, which means you need to replace the valve cover gasket also. some auto stores sell a kit or you can buy them seperate(valve cover gasket, spark plug grommets) from the dealer. its actually not that odd for this to happen on cars cuz over that 100k that rubber has been subjected to heat so it just goes brittle.