Well sometimes I have been out and about at 0600 for example Stockholm arrival through the islands, fiord passage etc and/or early morning swim. I daresay some pax were up and about and would have heard the corridor announcement so an all ship announcement was correct as majortom10 states.
In any case we don't have the responsibility of the safety of the ship and all on. boarrd. The captain does.
In a different type of incident on QV off the NC we were in the theatre when a loud noise was heard creating a certain amount of panic amongst some. I thought correctly that bow thrusters were being used.
The OOW had sighted was believed to be a body but reached turned out to be a large bulk of timber. The ship had turned almost 180° to investigate.
An all ship announcement was made shortly after allaying any concern.