Friend Dropped iPhone. Is it okay?
Your phone is fine. The Speck CandyShell cases offer excellent protection. In general, the iPhone often takes falls quite well with the particular exception of shattered screens if it falls onto concrete/rock. I dropped my previous iPhone 4S multiple times and it was still in great condition. One time it fell from about 3' onto concrete and survived with just some scratching and minor dings to the metal. 

As a side note, my personal opinion is that the Speck CandyShell (while they last) is not at all far off from the Otterbox Defender that many people have: so you phone was well protected. I suspect you wouldn't notice a difference even if there was no case, though with that fall. 

So, don't worry about it and your phone is just fine.