Disney has released a new Lion Guard clip, that also ties in with their Disney Channel movie Descendants.
In this clip Simba is shown to still be worried about the safety of his cub(s). It seems that in the clip Rafiki has told Simba, Kion's role in the Circle of Life. Simba's reply is to nervously say, "He can't possibly be ready, he's still a cub."
As we know in Lion King 2, Simba was overprotective of Kiara.
It seems some things never change...