The thumb stud is press fit into the blade, if you've got access to an arbor press you can remove the blade from the handles and press the thumb stud so that it is centered in the blade, without a press you might be able to correct the problem with a few taps of a hammer with the blade supported on a piece of wood or plastic with a hole for the thumb stud to recess into. If you press the stud too far trying to push it back the other direction it might cause problems though, the thumb stud might become loose in the blade. If you don't have any experience doing this kind of work or you're concerned about cosmetically damaging your knife, send it back to Kershaw for a proper repair, they've got the right tools to do the job.