Trixie did this for a while...to the point that she would wake me up in the middle of the night licking them! We called the vet and they said it was probably allergies and before bringing her in to 1) make sure her nails weren't overgrown and poking her (which they weren't) and to 2) try changing her food first. Change her food, she stopped within a day or so. Also, make sure she hasn't walked on a freshly mopped floor or sprayed lawn or a flowerbed w/ pine mulch/bark...they treat mulch to prevent if from becoming infested while in a bag on the shelf and they could have a reaction to the chemical used. (I would have never thought of this, I was very glad they pointed it out.)
