"_____'s Spirit is Fading Away" Message. What is this?

I got this notification as well just now. I have MC Command Center and I make sure to flag the sims I do not want culled because culling means they disappear from your sim's family tree. The ghost notification was for a sim I had already placed the Flag This Sim To Not Get Culled. Will the game overwrite MC Command Center's culling if I ignore the message? I have the latest update for MC Command Center by the way.