I do believe Cathay did have a slide deploy recently in flight. It was on the new A340-600 which has the escape slide for the overwing exit built into the wing not the door. This has somehow been faulty and deployed automatically.
A passenger did bring a banging sound to the attention of the flight crew. I do believe the Second officer went back to look and could also hear the noise. Later inspection from the crew showed that the slide had been ripped off.