It's play only. A 10 week old puppy doesn't even really understand how to show aggression. Puppies will bite everything, including the hand that feeds them and the hand that tries to correct them.
Search this site for bite inhibition. Believe me we've all been there before. I wondered if there wasn't something wrong with my dog because she was biting me so often.
Cedar - August 8, 2010
Titan - October 20, 2011