I have a kitten which does exactly that to my dog. Never cease to amaze me how my dog is so calm about it. Her teeth are needle sharp (and I know this from personal experience...).
Thanks for the compliments. Despite how rough this looked, they really seemed to have fun... At this age (5 - 6 weeks), they are playfighting every second of the day that they are not eating and sleeping ^^
They are so cute. Very Joyous.