agressiveness/size

Question
I live in the city but there is a good bit of woods around so my question isnt so much why are they here it is inevitable I guess. My question is last night at dusk almost dark I was walking down my walk way which is grass on both sides (not much, normal subdivision size) and out of the corner of my eye I see a frog jump towards me, I said that is weird a frog jumping at me so i turned and low and behold he jumped again but the frog was a 13 inch North carolina copperhead. I am positive as I have been in the woods most of my life and right down to the green tip on the tail it is a copperhead. I am curious as to why he struck at me as I walked by??? I read that they generally freeze when they are scared...well he sure wasnt and struck a second time when I turned around. I was appx. 6 inches from him so when he struck he missed me by 3 inches. I have to admit I am bothered that there was no warning but hey thats his defense???? against me??? anyway to your dislike i am sure he is now dead. I had no other choice there are way to many kids and animals for a venomous snake with that kind of attitude to be around. I have no issues with black gardner or any un venomous snake or a venomous in that matter long as they are in their enviroment. I know I know I am in his enviroment but not really there is alot of woods around and i am sure he was just eating. I am sorry to ramble I just wonder if you may know why all the aggressiveness?? and how old is a 13 inch copperhead?? I am curious as to whether I may have a nest or if he was old enough to be out hunting alone. I have inquired with my neighbors which have lived here a long time some 27 years and nothing besides a common black snake. I do have a neighbor behind me that says he thinks his cats have killed some small copperheads over the years but he wasn't 100% sure if that was what they were. Any help would be greatly appreciated!
Thanks
Jason

Answer
Snakes hunt on their own from birth.  They hatch/are born fully capable of finding and killing prey.  The small size of the one you found means it was young; I'd guess a year or less.  Young snakes are more defensive than older ones because more things try to eat them.  I would not worry about a "nest."