I would just let it go. It's possible that Avis is already aware of it and noted it on the vehicle's history. Or they consider it so minor so as not to even note it. In any event, there's nothing for you to do about it, unless you want to have it repaired at your own expense at a windshield-repair place, to guard against the risk of the chip expanding into something larger.

Did you charge the rental to a credit card that offers LDW?