Congratulations! It happens. My husband had his green card in hand in less than 3 months (submitted AOS toward the end of May and got the green card in the beginning of August with no interview required). We were confused and surprised, but happy!
We sent ours in on the 22nd to the Chicago location. Haven't gotten any notifications from them yet but the money was just taken out of my account this morning, so we know they got it.