It may have been set too low when originally staked at the factory or gradually driven back during shooting.

Notice from the hammer side, you can contact the back side of the bushing thru the firing pin slot with a flat bladed screwdriver tip. You can gently tap on the bushing and see how easy it moves. If it moves easy, it has to go back for replacement. S&W or one of their authorized repair stations will work on any Smith with a Model # on it (starting 1957). So yours is not too old by far.

If the bushing is tight, drive it flush and see if it stays there after shooting. You have nothing to lose by trying. If it sinks back in after shooting it, again, it needs replacement.

__________________
Jim
S&WCA #819