Strange noises coming from ?

I've recently bid farewell to my virginity. While I am having with my girlfriend, I hear strange noises coming from my her when I am moving in and out. Neither I nor my GF encounter any uncomfortable feelings and on the contrary she seems to be having a great time. What's causing this? Should I be worried? Is it normal or there's something wrong with her? I haven't had with any other girl. We both are each other's first so I don't know about other women. Please Help!!!