"Available Reserve Space" failure(?) on new SanDisk Ultra II 960GB

I have just installed a brand new SanDisk Ultra II 960GB (X41100RL) on slave SATA port and also saw the same message in SanDisk Dashboard.  I am running Windows 10 Pro (64 Bit) on an Asus P5W DH Deluxe motherboard which has a JMicron JMB363 Serial ATA controller.

Would be useful if someone knows if this is a software bug or a defective drive?