Honestly, he believes it's benefitting to the both of them. She needs to know how extraordinary, how important she is, and he is beginning to realize that some things can still surprise him. It makes him more invested in 'life' and in humanity. He becomes more emotional over all and less cold, old and detached from the world at large.
"Now, would you like to discuss with me what's on your mind?"
Because he's certain that this isn't Sookie simply practicing with her light for her own defense. She's got something on her mind. He just has to get her to confess what it is.