Issue with metamask pop-up window

Today, I installed MetaMask chrome extension. After importing myetherwallet account in MetaMask, I loaded beta.cent.co. But before that I logged out from MetaMask. As soon as loading was finished, MetaMask login pop window opened automatically which was showing in the middle of the browser. Have a look at here:

It generally opens at the right upper corner of the browser when users click on the icon. But this window is not attached with browser. This absurd behavior prevented me from login to MetaMask. Since then I have loaded the cent several times, but it showed the same result. However, when I opened another site, the pop window didn't open. I am little bit confused and not able to decide whether to login to MetaMask. Could anyone please help me to know whether it is correct?