iPod nanos Really Hot - Literally - in Japan?

Months ago I wrote about an Atlanta man who said his iPod nano ignited in his pocket. Perhaps Japanese authorities need to speak to him.

An official at the Trade and Economy Ministry, which oversees product problems, said a defect is suspected in the lithium-ion battery in the iPod Nano, model number MA099J/A. This would be a first generation model, just as in the earlier story. According to reports the device shot out sparks while recharging.

Apple hasn't denied the incident; indeed they reported the event to the Ministry this month (it occurred in Kanagawa Prefecture in January). They haven't, however, commented on the issue.

It should be noted that late last month another nano of the same older model was reported to have "exploded" in this Apple support forum post (nano pictured above).

Based on these multiple reports, would a thorough investigation turn up more events like these? And should consumers be concerned? Honestly, would anyone be truly surprised if this was another Li-ion battery problem? Though it's the batteries in laptops that we generally worry about, this is the same battery technology, after all.

At the very least I'd be wondering if Apple is getting batteries from Sony.