Might wanna post in the kershaw/zt forum. An actual Kershaw employee is the mod.
My best guess is that either the torsion bar (spring) is somehow weak; or that the pivot screw is too tight.
Grab a set of mini torx screwdrivers and loosen the pivot screw just a hair and see if that helps. If it's still not right, disassemble (it's not hard) and check the torsion bar/reassemble (search the tube for how to videos if you like).
Of course the trump card on any KAI products is to send it to Kershaw and they'll either fix or replace it. But they'll also send you spare springs and such small parts to fix minor issues yourself.
I truly hope that your pivot is too tight, and that you'll be enjoying your new knife in no time.
Good luck; I hope this helped.