DAE's colon sometimes not completley close when you fart, leaving a lingering waft behind you?

The worst case of this happened recently, there's a receptionist in my building and a door between the main entrance and the receptionist. I farted in that little buffering space... but as I motioned to open the door I realised it was persisting. After already being seen to open the door by the receptionist i couldn't back down and run away.

She tried to hide the slightly confused expression of disgust on her face but did not manage it. I just smiled and initaited normal conversation.