Facebook adds the Confirm link automatically when their systems detect that you might be cheating or otherwise gaming the system in some way.
If you continually like and unlike the site, even in testing, then you can trigger this mode. If a number of users Like your page but then remove the resulting post from their FB walls or mark it as spam, then you can trigger this mode.
There is no way to un-trigger this. They can't even manually untrigger it. It will resolve itself over time as their system detects correct usage.
And their data actually does show that people do click the Confirm link.