The bottom panel of the notebook may become warm due to the CPU operation and/or battery charging. This does not indicate a malfunction of the computer. The actual temperature varies depending on the peripherals and software you are using and the length of time that the unit is in use.
WARNING: Do not use the notebook computer on your lap for an extended period of time. Extended use of the computer or adapter may cause discomfort. Do not cover the computer or adapter with clothing or blankets when the computer is turned on. Covering these components may result in damage to your unit.