What time was your delivery? Mine was at 5:40 and there was an M5 that looked a lot like yours behind mine. When that M5 was started up my wife looked at me and said "wow!, what is that?" lol.
Edit...I was just going back and looking at some of my pictures, and that was you! Gorgeous car and congratulations. Here's a picture I took from the stairs as we were walking down. You can see your M5. My car was the one closest to the stairs as you come off.