Saeril didn't want to tell Yavanna of her natural power; not yet, anyway. She didn't want to freak her out and say that she would know her every thought, but it would be amusing to how confused to princess would be to [i]how[/i] received such private information. It was her secret way to understand her surroundings, as well as other people. Whether they were to be trusted or not. A perfect asset to provide the right sources to ensure Kili's and the princess' safety. 

The elder chuckled at Kili's teasing and it amused her to how much they can act like children to each other, with her to be the mother of the group.