Most Helpful Girl
Doing a favourites list and not including you means exactly that. You're not on the list. If she wanted you to see it, then she's letting you know it. If you weren't meant to see it, maybe she's just thinking about the things that are quite close and dear to her heart and have been for a longer period of time than however long you've known her. If other people are on the list, consider if they're family and long-time friends. You could just joke with her and say, "I see you forgot to put me on that list." See how she responds.