On further inspection, I don't think it's a re-grind.
From looking at the box of caps and shells that came with the crank, it looks like it was fitted with a mixture of Green and Yellow shells.
(Hence, the Green and yellow blobs of paint). I think they are the original factory assembly marks.
My plan now is to the check the bearing clearances with some of that Plastigauge stuff (
http://www.plastigauge.co.uk/index.html )with a new set of Yellow shells to see if I need any Green ones.