1680 red - “tiny”bottom right lug. Known defect?

[mattg6]

Now seem to 1680 red subs with a “tiny” bottom right lug. The camfers look factory and they’re presented as unpolished. But they’re clearly skinnier than the other 3 lugs. Was this a particular factory that made these and/or a particular period? Service case? Anyone seen this or have an idea

I have confirmed it’s not just the photo or lighting - in person it’s clearly smaller and I guess just came from the factory that way? Thought it was one off but have now seen two