I think mine is lifted more than yours lol. I honestly forget it's like this.So I guess my phone's back glass became worse over time. I didn't do anything special with it, just used the phone. I don't think it's waterproof anymore at this stage. I also believe that the lifted back glass extends almost up to the power button and also halfway to the right corner of the device on the upper back side!
Have a look at the photos. The first three are magnified, the fourth one is the original size to get an overview about the issue.
I'm going to post this also on the Sony support thread (http://talk.sonymobile.com/t5/Xperi...-plates-backs-coming-loose/td-p/346370/page/3) and since they allow photos now, I'll see if I can attach some "eye candy" to my posting there!
Sent from my C6603 using xda app-developers app