Everything was great and the Superbar integration was quite smooth.
But I don't know how after a certain time, the Superbar integration no longer worked. It was quite irritating and it seemed to be a bug on the Firefox beta which stopped the Superbar integration.
I did some googling and I came across a website which tells you how to disable the Superbar integration for Firefox. Logically, the bug automatically disabled Aero Peek in my case. So I tried to bring it back using the following way:
1. Typing about:config on your browser.
2. Looking for browser.taskbar.previews.enable.
3. Making the above false.
It was that easy to bring everything back to normal. And you can also do the opposite of the above to disable Firefox beta Superbar integration or Aero Peek for Windows 7.
PS: Thanks to Carrot for bringing my attention to Aero Peek BTW!