That's very doubtful. The earliest DM-2s observed so far has 6 digit serial numbers starting with 06. Most likely the silver screw was replaced with black screws at the same time that the 6 digit serial numbers was introduced (serial 000000). That's 6 months before the first DM-2s popped up.
There have been several silver screw DM-2s on Ebay over the last few years. Most likely these have all had unoriginal screws. If you see another one, check the serial number. If it is earlier than 06xx00, then maybe, just maybe it's original. Otherwise it's definitely unoriginal.