Haven't sent mine back yet; need to. I've owned mine(a Pipeline) for two years and I didn't use it for about 8 months out of that. It wasn't sealing right, nor was it striking. I took the thing apart myself and got it to seal again, and I replaced their flint with a Zippo flint. It's been acting silly again, so I'll send it off pretty soon I think.
It seems the vast majority of problems I've read about(at least for mine) has been with a bad seal and it hardly ever lighting on a strike.