Wow, you're really lucky that wasn't worse. Head injuries usually do bleed profusely, just think of the trail of blood you must have left behind. I hope you heal well and soon.
I rode home after cutting my forehead playing at a friends house when I was about 7. I was far from home for me then, and knew it must have been bad when so many adults noticed the bleeding and asked me to stop so they could call my parents.