Yes, if anything Rolex has never been consistent nor does what they do make any sense to anyone but themselves likely. The 1530 was also available as a chronometer grade. It is earlier than 1570. Generally the dial reflects what the movement is. The 5512 being the higher grade watch fitted with a chronometer grade movement...generally...the 5513 being the entry level non chronometer...generally Ha Ha. We may never know for sure what was up. The minute tracks for both of those models on all the examples that I have seen have been just dashes open to the edge not closed or boxed as the one on yours is. Could just be a variant. I have been trying to gather all the examples in my head to try and make some sense out of it. At this point it seems that the 5512's and 5513's had open minutes and the earlier 6202, 6536, 5508 non crown guard models had closed. Boy I would love a definitive on that one!!! At any rate it is a very nice watch that you have in very nice condition. I am playing detective with a few of my own. ():-)

Best regards,