I think Dave did some research on this originally, if not he will let us know, and arrived at the conclusion that all gas knobs leak and they are rated in terms of how much gas will leak out the shaft under certain conditions. That is, since the knob turns, the opening for the shaft must be slightly larger than the shaft or the shaft will stick and will not turn. ( for example, if you mill a hole that is exactly .250 diameter, and try to take a shaft that is .0002 smaller in diameter, you will need a press to force it into the hole, but it will not rotate) My recollection is that the amount of gas that leaks depends on how well the knob assembly is machined, how high the pressure is at the supply side of the knob, where the propane is coming from, and how high the back pressure on the downstream side of the knob, in our case the burner. For the BS, no big surprise, the valve assembly is not the highest precision. Also, the burner is a high pressure burner, which means the back pressure is much more than you would get with your standard gas grill. With the red regulator, if you turned it all the way up, you then put the valve under the worst conditions and you could end up with more gas escaping than if the supply was at a lower level. I don't work for BS, but my guess is that they tested and found that if they kept the input gas at or under 5 psi, the amount of gas that would leak out the shaft would not be enough to ignite. Of course, if the shaft gets hit during shipping, and the valve assembly loosens up, that would change things. I don't mean to downplay the concern, obviously, you don't want to set someone or their house on fire. I actually have a little experience with a propane torch with the same issue - shaft must have developed a burr, and the plastic knob of the propane torch caught fire - to make things worse, the knob is the only way to turn off the propane. Fortunately, I was able to blow out the flame and then using gloves, turn off the knob, but agree that is not a good place to be.