I have 187 + or - 2 Leeks and while I don't carry each one, I have not had one open on me.
I've almost had one open on me though.
My own fault though, digging around in my pocket, safety off and my keychain caught the thumbstud.
While digging I moved the Leek back towards the middle of the pocket.
I normally carry a Leek tip-down with it sitting in the front of my pocket.
mainly because I usually have a ZT or Groove at the rear of the same pocket.
When a torsion bar "wears" out, it might not have the tension to hold the blade in place anymore.
Replacing it might be a good idea and would eliminate it if that is the problem.
If you feel you can take the knife apart, contact Kershaw and ask for a torsion bar for your Leek.
They'll send it to you at no charge.
If you don't feel like you can tackle the assemble/disassemble then send
it off to their repair dept and they'll fix you up.
Either way, they'll help you out the best they can.
mike