A friend's Sherwood Oasis SRB7700 regulator was leaking a small, steady stream of air (evidenced by bubbles) during a recent dive. Upon inspection, the leak was found to come from a plastic plug on the regulator cylinder (I believe it's the 2nd stage). When he took it to an LDS, they told him that it's normal and by design. Does anyone know if this is true? And if so, what is the reason for this design? Doesn't it waste air?