That's developmentally appropriate behavior, and a sign that she's independent and learning to monitor and attend to her own emotional needs. You should be a proud mama. =D
We've always coslept.
Dd10 mostly sleeps alone now. She comes in about once a week on average. She snuggles and falls asleep, but moves back to her bed in the middle of the night.
Ds will be 13 next week. Maybe once a month, he'll ask if he can sleep in our bed...but he doesn't. lol He'll stay in my room for a little while and snuggle...then go sleep on the couch or back in his bed. More often now, he's started just asking if he can hang out a little before bed. We all read before bed, so he brings his book and we lay in bed reading. After a while, he gives me a hug and goes back to his room. That happens on average about once a week, too.
It's not like one day they are suddenly completely independent adults, you know? If you allow them to transition naturally, it will be a slow and steady change. The kind you don't realize is happening until you look back, you know? =D It sounds like your dd is maturing in an emotionally stable and nurturing manner.