Look like cracks are appearing on some Sony Xperia X1 phones. The cracks are appearing on the silver models near the stylus well and in the battery compartment. The cracks seem to be limited to those made in Europe and a production week. A lengthy discussion is on going over at XDA Developers on this issue. In reading the XDA discussion, there doesn't seem to be any consistency in the cracking and the problem may be limited to the production week (08W44-08W46 as indicated on the Xperia's Information Sticker). Sony's response, according to the XDA discussion, ranges from replacing the Xperia to having it inspected at a service center. The response reported seems to be dictated by the user's local laws pertaining to goods and services.
The Xperia isn't alone in having cracks mysteriously appear. The Palm Treo Pro had a similar problem a while ago. Could the cracking of the Xperia be behind the month long delay with the U.S. release of this phone? Could a quality control issue be one of the reasons why Sony and HTC has parted ways? The slider on the Xperia does shift up at a slight angle, could that shift be causing too much stress on the chasis of the phone? Regardless of the "why" these cracks have made a lot of Xperia users unhappy.