laptop hinge

Hello
i had my acer aspire 15 laptop for about 10 months now and the right side of the laptops hinge broke. at first there was a little gap but then after a week or so the plastic cover bit comes off so i can't close it and take it to school anymore. i took it back to the store i bought it from but they refused to fix it cause they believed i damaged by dropping although i never did. i opened up the backcover and found that the plastic bit that the hinge is connected to is broken and thats what lead to the hinge itself to snap. Since this is not a problem i have caused i was wondering if i had to pay for it or is this something covered by my warranty?
thanks
Tom