My 6 y.o loves his (now 10wk old) pup. He lays down and they roll around, he (my son)gently pushes pup and pup will jump and mouth him... its like watching father and son rough-house each other. Wags (the pup!) is generally well behaved about biting, in all situations and knows no means no. Is this play encourage wags to bite, do I stop it?