One of my friend got his I485 approved before I140. And later he got a letter from BCIS, telling him that his I485 was approved prematurely, and took it back. But he finally got it straighten out and got his GC. It was a couple of years ago.
Remember, those who work for BCIS are human beings, people make mistake. So, what's the big deal of having a case or two approved recently? It doesn't tell us that retrogression doesn't exist.
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