My new ipod touch battery dies fast? Could this be iOS 5.0.1?

I got my ipod touch 1 week ago and my battery dies so fast. 25 percent gone in 1 hour! I turn off all background apps, brightness is low, push notifications off, no emails and no gamecenter etc and it still dies at the same rate. And I just use safari and facebook and 25 percent gone in 1 hour 😟 What is wrong with my ipod touch and how do i fix this? I bought my ipod from amazon so idk what to do since i have a battery issue. Is this related to ios 5.0.1 or is it my battery? Which is most likely? My iPod Touch dies in like 4 hours light usage...