Serious Account Concern (SE Logged me into another account)

So I just reclogged into the game with my username and password.

Then my character screen showed an EU world (not mine) and someone elses account with their character names...then in red on the center of the screen it stated:

"Please Update your Server List"

I immediately logged out but this is a cause of great concern....how did I logged into someone else's account from Europe by using my username and password?

http://files.gamebanana.com/img/ico/sprays/haaax_5.png