Why does she keep saying aww every time we talk?

First of all she said aww before when I got hurt or I say something nice every now and then but now she is saying it more often when we talk. Sometimes I would tell her I could take her to lunch and she would say " awww" but before when I asked her to lunch she would just say no thanks or another time. I don't mind her saying it but it's just weird that she says it Everytime I get sick or I say something sweet to her when many months ago she reacted differently to my gestures. I happen to really like her just so you know.