Disturbing or overrating?

hey ladies let me paint this full picture for you,
Im currently a nanny,I say nanny because i go more than baby sit i cook clean home work. i see them kids more than there mother (she even has to ask me dress sizes and if they need cloths) There ages are, Brendon 9 Adam 8 and Karlie 4. (yes 4) but keep in mind she is a very smart girl.

She is the only girl youngest and the mother spoils her and treats the boys like they aint around to the point they start to act out just for attention.

But on to the story.

Cloie was taking a nap while i was doing the dishes and cleaning the kitchen, Brendon was taking out the trash for me, Karlie was sitting at the table drinking. I hear cloie moaning so i took her out her crib(travel crib i keep there) to put her in the swing while i clean. And Karlie say's "Oh i though cloie was dead and you buried her" then laughed! I had tell her get go in her room because i was fuming (you all know how we are about our little ones) and i did not want to cuss this little girl out so i said Karlie go to your room now. Am i right to think this is disturbing coming from a 4 year old? or am i overacting? The whole thing keeps playing on my mind.

I think she should know it is very wrong,and I would tell her mom what she said and let her know that you sent Karly to her room (as would I have) and that it really upset you.At the same time,a 4 year old to talk about death in such a trivial way is NOT unusual.Teo says 'oh I died' and then falls over and it's his way of playing,they don't 'really' understand the concept of death at that age,even if they are smart IMO>She might have seen it on TV she might have heard it from another kid,especially with older brothers.I am not amking excuses,in fact when I read what she said my heart stopped for a second coz I was so shocked,I am sorry she said that because it seems so cold and that she doesnt care.Either way I would tell her mum,but you did the right thing,maybe have a little talk with her and tell her that it is not ok to joke about people dying,espeically children as it's mean and show that yoy don't care and tere is nothing worse than people NOTcaring.I would let her know it upset me and made me sad,then leave it at that,she may appologise,she may just absorb what you said but she needs to understand that it's not ok! hugs hunny! xxx

I did explain to her the same day that it was bad and means somebody going away forever and made me very sad and i also told her mum her mum didnt care at all she just said ok cya tomorro