How far did you drop it? Also did it land on a sharp or pointy object? Gorilla Glass is really durable for phones but keep in mind it doesn't have the same durability as Metal or a diamond. Be careful with your phone and if you don't have a protective cover for it, you will want to invest in one.
Also, accidents do happen (as I have dropped my phone a few times) and I want to offer you a piece of advice. Every time I drop my phone I stick my foot out so that my shoe lessens the impact of the fall (this does require fast reflexes) I've dropped my S3 on my shoe about 3 times now, and not a scratch to this day. I hope you find this piece of advise useful, and remember be careful with your device.