I checked and it appears that the site did not recognize your IP address, which was why it showed the default "Hello". German IP blocks were already tagged with "Guten Tag". How can we miss out Germany?
It'll probably show up correctly the next time you come back. If not, it's because your ISP is using a new block of IP addresses that has not been updated yet in the IP range to country database that we're using. This should be fixed in future updates of the database.