Same auth. code with DOMAINCA.com ... what would you do?

[alwaysthinking]

I won a certain domain name at AFTERNIC.
Paid the afternic escrow.
Domain is registered with DOMAINCA.com.
Seller transfered the domain name to an account I opened at DOMAINCA. (domain would have been in my account with godaddy if the guy would have just waited a day more and I would have felt more comfortable).
But i see the auth code is same as original as what seller had when he had domain in control.

Now is this a 'iffy' situation?
Do you guys have any experience with Domainca?
Is there a way to get new auth. so that seller cant pull back this domain after I pay?

I mean it would be hard to chase someone in Korea, hence my worries.

 

[Rockefeller]

Lock the domain name and he can't pull it back, auth codes are issued through the central registry.

 

[alwaysthinking]

Registrar changed the auth code after I renewed the domain for another year. I feel much better now.