Otterbox defender rubber portion is not a tight fit?

I got an otterbox defender case for my iPhone 5, and the rubber part around the hard plastic case is not fitting tightly around it. I bought a defender with Verizon when I first got the phone, but returned it and bought the same one from Amazon since Amazon had it for a lower price. The first defender had a nice and tight fit. For some reason though, this one does not. The rubber part easily comes off. Does anyone know why this is or if I can fix it to make it tighter?

Here's the link to the product on Amazon: http://www.amazon.com/...009A17D4Q/

I noticed that otterbox cases from Amazon have some defects, such as dirt, scratches, or it just doesn't fit right. Don't get otterboxes from amazon, even if Amazon is the one selling them.