Apple has sent out emails to registered owners of 1st generation iPod nanos stating that certain iPod nanos created between September 2005 and January 2006 might overheat and pose a safety risk. This is because of a manufacturing defect from a single supplier, and the likelihood of problems increases as the model ages. Apple then directs the owner to a replacement program.
There have been some cases of the iPod nano's battery overheating in the past, and while a search on Apple's support site turns up a document, the link is currently not active. The issue turned up previously in 2009, and
