Today Nikon recalled some of the EN-EL15 rechargeable Li-ion batteries ($64.95) that are used with the Nikon D7000, D800, D800E and Nikon 1 V1 cameras. The described reason for the recall is overheating. There were no overheating cases reported from users, the problem has been discovered during the manufacturing process.
How to check your battery - check the 9th digit of the lot number as indicated below:
If the 9th digit of the lot number is E or F, you must replace your battery. The support article is currently available only on Nikon Europe and will probably be published on Nikon USA site tomorrow.
Update: here is the Nikon USA service advisory page.