Why would an older kitten when being petted snuggle their noses to your face and not hard but bit your face?

When petting my older kitten she is very affectionate. But as she rubs her face to yours she will at time bit you, then after nipping at your face still wanting to rub her face to yours. She isn't bitting me because shes mad of hurt. She only does this when shes being affectionate. I never had a cat do this, only if they wanted your attention and your not giving them love.