In long-term storage, the other issue you might face is the flint starting to swell. It's probably a slow reaction with moisture in the air. Consider wrapping or sealing the lighter in a bag. Check operation once a year and before major trips.

If the flint does stick, you can usually dislodge it by whacking the lighter's base, hard, on a fixed surface. I've resurrected quite a few that way. I've also experimented with a teflon spray lube, which doesn't seem to interfere with sparking ability; but I haven't used it long enough to say if it works.