If the pivot is a screw, you can try loosening it and playing with it as you retighten it to center it. Sometimes works.
Sending it off for warranty depends on cost. If it's a +$50 knife (choose your value), email the company warranty/repair department concerning the problem and send it off.
Me, a bit of off center doesn't phase me until I'm in the +$100 range. If it doesn't rub and functions as needed (locks are a bigger issue to me), I'll live with it.