I have had cats all my life (the parents had a cat before they had us kids) - and have always found girl cats to be a little more independent than boy cats. One of my girls, was very attached to my other cat - to the point that she really didn't have much to do with me. Her companion cat (a male) was always in my lap and slept by me every night, but she, not so much. Until she hit about 12 - then she suddenly became very lovey dovey with me and my son. Would sleep *on* me, get on my lap, ask to be petted. All very weird for her. Took her to the vet for a check up - she was very healthy. It just took her 12 years to realize that I was more than just a source for food, water and a clean litter box. LOL
Run your kitty into the vet for a quick check up, just to be sure, then just enjoy the new attention you are getting from her.
Who really knows what goes on their little cat brains.
God Bless