Hard to know what happened to the cap in the pic above. Chromic anodizing is very susceptible to fading...the anodizing may have still been there. It is super common to see controls, master cylinders and caps that have faded so much that they have no black on them at all.
I have never seen an original cap that was gray. Only faded ones and those that had been stripped. Though there are many changes to the sandcasts over the few months that they were produced, the anodizing does not appear to have changed based on documented cases.