wow, that's low, not necessarily bad though, the only effect it will have on you is that you'll get cold a little easier because you have less insulation, just make sure you are well prepared for cold weather if you are around it.
It's fine if you were older and were working out. Most body builders have close to 8% but I think it's really low for your age. Ask your doctor if you want gain some weight. It also could be you're just naturally thin.