I bought an L4 a little while ago that had a very hard to operate switch. One day it turned on in my pocket. When I pulled it out I was not strong enough to press the switch and turn it off. I played with it quite a while, banging on the switch before it was freed. It now worked smoothly, but the light was always on. I called SureFire. They sent me a new one, and I returned the old one.
I don't know if this is the same problem that Mrdi or Gary have. I hope not, but if it is, you may find one day the thing won't work at all.
Paul