I called them up and found out some things:

-Too much international traffic may cause your account to be banned.

-There is nothing in between, ie they won't send you a warning message stating that you are getting too much international traffic. Once it hits a certain point, your acount is banned.

-It can take up to 45 days before this determination is made.

I have a site where people from everywhere come to visit so now I'm rethinking putting up so many YPN ads as there is no way for me to know if I am sending too much international traffic.