Rowan has already seen Jalene's angel, talked to her angel, and even painted a picture of her angel (which just happened to look just like her, when she had hair, which he had never, ever seen)...so it is kind of hard not to believe what he says when it comes to things like this.
Rowan had been right. God told him it would be today. He had a peace about it. Her Mom had peace today. And it happened today. How can you not have faith when you hear something like that?
I think that is the message here...Jalene's life was a short 4 years, but the lives she touched, the strength she exhibited, the faith Rowan's stories about her gave people...that is more than someone who lived 400 years could ever give the world.