Is it normal to not have any sense of self-preservation?

I been wondering this for awhile now, I just don't seem to be scared of being harmed or dying. This one time I was walking home and there were these black guys on the other side of the street and one of them looks over and points at my and one of his buddies walks across the street toward me and he asks me about my iPod and then starts to walk behind me givin the a-ok symbol to his buddies every now and then. So I ask him where he's headed and he says he's actually headed back towards his friends soon. I tell Him i figured as much and ask him if he's gonna tell me what's going on or is he going to just keep me in the dark. He say his buddies told him to come and rough me up. So are you gonna take my stuff too, i ask him, and he say "nah man I'm just here to beat you up" To which I find myself saying "awesome I was getting worried there for a moment". He seemed kinda confused by my remark and continues to walk behind for awhile and he asks me "so aren't you going to fight back or run or something". I tell him no and he asks me why and I tell him he's done nothing to provoke me into fighting him and that I would probably lose anyway me being the skinny pale white guy that I am and running is no good cause my backpack is heavy and hard to run with, plus my house is coming up and as nice of a delequint as you seem to be I don't want you knowing where I live. We keep walking some more and he asks me like 4 more times if I'm sure I'm not gonna fight back. After the fourth time he rushes at me yells some curses and punches me once in the side of the head and runs off as I keep walking like nothing happened. By the time I turn around to see where he's at the guy is gone. So all that right there...is what I did normal?