Happy Behavior?

My cat is 2 years old and developed this new behavior well outside of kittenhood. After I lay down for the night, she comes up to me and starts kneading my arms or chest. It is different from her kneading behavior as a kitten. This is much more pronounced and deliberate. Her eyes are closed and she purrs up a storm while she's doing it, so she's obviously happy. When she's done, she curls up for the night right up against me. She's too old for kneading, so what is she doing? Is she scenting?

Many cats carry the kneading behavior into adulthood. Its a way of marking you with their scent as well as just generally being affectionate with you and expressing their contentment!
My Oliver is three and is a big kneader- my stomach, the couch, his bed, my bathrobe, whatever he can get his paws on!
Sounds likes she's a very happy, well adjusted kitty and enjoys being your fur-baby!