If a situation arises, such as this porous head diagnosis, with unusually low mileage such as the this poster describes, the Chevrolet District Service Manager is in a position to provide a 'Customer Satisfaction' arrangement.
This could be in the form of a full warranty payment or a partial payment.
But you get nothing without asking the dealer to get the DSM involved and ideally the owner should be available directly or by phone if the DSM wishes to discuss the concern.
Notice I said the dealer must initiate the request, so don't bother rattling Chevrolets cage. The folks on the phones are not in a position to over ride warranty or make case by case decisions.
Make certain you have good records of service to support your request.