April 2019: The rear hatch seal on C4's are prone to splitting/tearing at the corners. GM simply glued the corners of the hatch seal together at what looks like a 45 degree mitre joint. When you close the glass hatch the friction of the glass against the seal tends to make the seal split/tear at the corners. You can help prevent this by keeping the seal clean and applying a light coat of silicone grease to the seal.

Since my car's hatch seal was already split/torn when I purchased the car I decided to buy a new hatch seal from Wilcox Corvette. They sell a hatch seal that has "Molded Corners." This new design tends to make the corners of the hatch seal much sturdier. When it arrived, the packaging said Corvette America???