Is that reason somehow not good enough for you? She failed to wake up several other people in the same hallway.
I'm the same way. I fell asleep the other night with our baby right next to me in her basket. In the middle of the night she was screaming her head off and my wife said I never budged. If you want to wake me up in the middle of the night you'd better make your knock sound like my cell phone.
Nope, it's perfectly fine, I have slept through earthquakes and hurricanes.
Look a couple posts up, it was exactly what I had guessed.