Sony SGPT11 - Manual (Page 131)

Heat builds up in the tablet device and the AC adapter while the tablet device is in
use or being charged.
Heat builds up in the tablet device and the AC adapter while the tablet device is in use or being charged. This is normal and
should not affect the performance of your tablet device.
The tablet device can be shut down for safety when overheated. In this case, use the tablet device in a cool area after the tablet
device cools down.
If your tablet device becomes abnormally hot, it may be in need of repair. Turn off your tablet device, unplug the AC power cord
(mains lead) from the AC adapter, and stop using the tablet device. Contact the service/support center named in the warranty.