Dan gives good advice about allowing her to tug at your lips, she might not be hurting you now but it could lead to a nasty bite someday, also we have bacteria in our mouths that could potentially harm Shelby and you don't want to make her sick or it could even kill her, better to distract her to something else than risk putting a fat lip on your pretty face. Otherwise its cute that she is wanting your attention, focus on me is what is on her mind.