...from what I can glean from Panerai's releases, the coating process isn't the usual dip-in-electrolyte-tub-connected-to-a-battery style anodising. Instead of forming Aluminium Oxide, the process (google 'Microplasmic') uses masses of AC power to form a ceramic layer.
That said: I agree that it is a production fault. It looks like there were some contaminants on the caseback before coating, with pitting the longer term result.
I am of the opinion that these processes (microplasmic, PVD, CVD, etc) were originally developed to increase engineering properties of materials (wear resistance, hardness, etc) and were never intended to obtain the level of cosmetic perfection (colour depth, uniformity) that the likes of a watch case 'requires'. To obtain those cosmetic properties, the engineering properties are probably compromised.