I wish I knew, graduation2003. A 3 week wait is not out of the norm, some people wait 4 or more weeks for an approval, others as you know get approved a couple days after sending the RFE response.
If I had to take a completely uneducated guess, I would say that there may be a smaller group of adjudicators working exclusively on EB1 applications. I believe that each EB1 petition is very unique and requires a different set of criteria than EB2 and EB3. So that may be why you are waiting a little longer than usual. But again, this is my own theory and it's probably wrong!
Let me make a wild prediction and say that you will be approved no later than the end of next week!

Good luck and please keep us updated!