Whether the captain tells the cabin crew first or not is not something I wish to go into, but if there was something of this nature - would you be more reassured by the voice of the captain, or one of the cabin crew ?
If there's some minor mechanical fault, I'd rather hear it from someone who knows what the component in question does and understands its relevance to the rest of the aluminium tube and can thus make a good assessment of its importance, as opposed to someone who may never have spent even an hour flying a plane.