When you shorten a link in Bitly, we pull the page title from the destination URL's page.
Sometimes, gathering this information takes a moment or two longer than it takes for us to shorten the link. In these cases, you might not see the page title when you first shorten the link, but if you refresh the links page, it should appear.
In other cases, we're not able to fetch the page title from the HTML. When this happens, we use the long URL as the title. You can always add a title when you shorten the link or afterwards, by editing the link.