I really wouldn't worry about it, it's highly unlikely it's been dropped from a great height, and tests by Bike magazine showed that only a three metre drop on to concrete made a helmet unsafe, so if it's been slightly manhandled I don't think it'd be great cause for concern.
As for the scratch, well that's one of the reasons I'd never buy anything like that mail order. The return postage would likely be more than it's worth I suggest.
Stick it on your head and go ride your bike
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