Apple has recently revealed that they are replacing first generation iPod Nano MP3 players in Japan if they are overheating.
Apparently all affected models were sold from September 2005 to December 2006, Apple say that some models overheat to the point that it deforms, which poses a risk of fire, according to SlashGear some fires in Japan have been linked to this issue
If you think your model is affected you should immediately stop using it and contact Apple, tell tale signs include discoloration or deformation and obviously a very hot iPod.
From what we can see it doesn’t look like Apple will be recalling models outside of Japan, which hopefully means that first generation devices in other regions aren’t affected.
Does your first-gen iPod Nano overheat?