Yeah, if you don't know for sure who can hear you, always assume the wrong people can. Once during an elementary school dance recital I commented that one of the cardboard records that were hanging over the stage was blocking one of the dancer's head. By the time the telephone game got it to her she was in tears because someone had said that her head was as big as one of the records. (fortunately I was the boss, so I gave myself a stern talking to and that was the end of it
) When in doubt, say nothing.