Originally Posted by
garykung
The problem was the O2 mask door, which I believe if the door cannot be shut properly, O2 will start coming out from the mask.
Not quite - oxygen starts flowing when the mask is physically pulled downward by the passenger (removing a pin and igniting the oxygen generator).
I was on a short (domestic) leg where this happened; they just let the masks dangle there for the duration of the flight. I guess they didn't want to do the same for a 13-hour flight though.