This seems odd. My battery powered clip on stand light was very dim a few days ago, even with good batteries. But about half way through band rehearsal, it just "popped" on to full brightness. And during practice at home today, it was a little brighter. But about 20 minutes in, it began flickering when I played. Is this just a light going bad and reacting to the air vibrations, just as it might if I was shaking it (like a flashlight might do)?