Evaluation of samples show parts lacked pliability about the hinge feature. Close examination of the hinge shows material separation in these areas (delamination). This condition is indicative of temperatures set incorrectly during initial setup of the process, or moisture in the raw materials. By testing previous and subsequent retained samples leading up to and after suspect lot number 841732219 (part number 308064000) in was concluded that the brittle hinge & improper closure was an isolated issue which was not exhibited in separate lot numbers.