The Japanese industry ministry is reportedly investigating a January 8th incident in which an iPod nano "overheated and discharged sparks," according to Reuters.

Apple's iPod safety manual currently states that it's normal for an iPod to feel warm, especially since the exterior of the iPod functions as a cooling surfaces that transfers the heat from inside the unit to the cooler air outside.

iPods have been known to overheat when placed in cases or environments that do not allow for adequate ventilation.

Stay tuned for more news on this as it becomes available and if you've run across similar cases on this end, let us know over in the comments or forums.