Challenging Supervisor's Defect Notification

NEC4 Option A.
All of the hollow core units for this project were delivered and the Contractor noticed and informed the Supervisor that one unit had a significant crack. A replacement was immediately ordered (no delays as the unit was not needed for some time), however the Supervisor raised a Defect Notification.

Can the Supervisor issue a Defects Notification for Materials that have not yet been incorporated in the works? It seems counterintuitive that he can, and I cannot find anything to say if the Supervisor has taken the correct approach.

Thanks in advance

Welcome to the Group
it seems strange to raise as a Defect if it is “materials on site”. If it is mos then no its not a Defect because it is not part of the works, see the definition of Defect at clause 11.2(6).