Nikon D5100 battery charger flashing? Normal?

I've just purchased a Nikon D5100 and following the manual, i've put the battery on charge. However the charger light is flashing orange. The manual says it shouldn't 'flicker'.Is this normal for first time charge or have i got a bad battery?

It should flash steadily until the battery is fully charged then, it will stay on constant. By flickering it means flashing inconsistantly/randomlly.