On one of the clusters in vCenter 5.0, I see a warning: System logs on host xxxx are stored on non-persistent storage

Recently we upgraded 4 hosts in two 2-node clusters to 5.0 U3. Why is one of the clusters displaying this message "System logs on host xxx are stored on non-persistent storage"while the other is not? Both clusters are using the default, non-persistent storage for now.

I have gone through KB articles but wanted to know why one of the clusters display that message.

Thanks

SDquality