Depending on the type and amount of ambient light in the room, you may see a flicker as the shutters of the 3D glasses open and close. This is normal and not a malfunction. If you find it to be bothersome, the flicker effect may be reduced by turning down any lights in the room.
Alternatively, selecting Cinema on the Scene Select menu may reduce the flickering as well.
NOTE: The flicker may be more pronounced when viewing content in 1080/24P format.