Awareness of death

My dear little GS (5) at lunch today asked me where my Dad is and I told him he had died - and he asked my OH and got the same response. He then said:"So neither of you have a Daddy" - it was clear from his body language that he had suddenly been struck by the awareness of mortality. A profound moment, which I hope we managed to handle sensitively. I cannot remember this moment of realisation being so obvious with my own children - but they had had hamsters and cats etc who had died.