It must be Gremlins

I noticed that my argon cylinder was almost empty so I went to change it. Turns out that the "full" cylinder waiting on the wall was really empty. No problem, I just drove 4 miles to the rental place to exchange my "owner" bottle for another. But there is some company name stamped in the neck ring, and it wasn't Airgas. Partially ground off and painted purple. So the rental place where I exchange my gas bottles says they are going to call Airgas to make sure the bottle isn't stolen. So I tell the gal at the counter that I got the bottle from them last time, only a few months ago. The last transaction they can find from me is 4 years ago. I go through about 2 ea. 200 cf bottles a year. I get them all from the same place. And they knew me. And I only get gas from them. So how would they remember me from a single purchase 4 years ago? So I call Airgas and they say not to worry, the bottle probably isn't stolen since the neck ring is painted purple. But then they say anybody can buy purple spray paint. So I'm waiting for a call. Maybe. Anyway, I need to be welding so I connect the bottle and even though the gauge says there is 2100 lbs pressure no gas comes out of the torch. So I check for kinks, make sure I can hear the solenoid valve working, check to see if the hose is crushed. Everything looks OK but still no gas flow. Then I look at the flow meter and it is not indicating flow. So I turn the little knob and the ball magically floats up and gas comes out of the torch. But I'm the only one in my shop and I wouldn't have turned that knob when I removed the regulator. And the knob couldn't have been bumped to shut it off that tight. Must be Gremlins, right? Or maybe I'm just getting old and forgot that I turned that little knob, which I never do. Nah. Must be Gremlins. After all, I am just across the water from Boeing. Eric