A sheath introducer system including a sheath introducer defining a lumen therethrough and having a proximal valve housing in fluid communication with a distal tubular sheath, wherein a proximal end of the valve housing defines a proximal opening of the lumen of the sheath introducer. A gasket seated within the valve housing has a first surface, a second surface and an outer periphery extending between the first and second surfaces. A first slit is formed into the first surface having an inner surface defining a first gap. A second slit formed into the second surface having an inner surface defining a second gap. A notch extends into the first gap of the first slit forming a bump on the inner surface of the first slit, wherein the second slit intersects the first slit at the notch such that the notch prevents the first and second slits from being in fluid communication.