T.M.
Is she working really hard to drink her bottles? You could try a bigger nipple size and see if she can handle it, you will know if she can't...she will be dribbling all over and/or gulping the milk.
Are her lips dry? She could have chapped lips. My daughter did when she was a baby and I just used Vaseline and Chapstick Overnight on her lips for a few nights and that did the trick. I put it on AFTER she was sleeping so she wasn't aware of it and therefore didn't lick it off. Your daughter's probably licking and sucking it because she can feel it and it may be a little sore. I'd say watch it for a few days and try changing the nipple and the using Vaseline and if that doesn't work, call the pediatrician. Also, does anyone in contact with her have cold sores? They are contagious. Basically, when in doubt, call the doctor and at least talk to the nurses there. They are usually very knowledgeable and helpful and that's what they're there for!