Quincymassguy - having too few shims in your LX does cause bolt stick. With too few shims, if the bolt is not allowed to move forward enough in the breech the stem cannot vent. This causes the bolt to hang, and is the reason shims are used. This can also cause it to hang if you place something (like a finger) right up against the bolt face, but not if you have your finger sitting a few centimeters off the face.
I have also experienced bolt stick when using too tight an o-ring carrier in the LX. If an extra shim doesn't stop the stick, try the next larger carrier. If it doesn't leak, that might solve your problem.