I literally forget my own name from time to time and I'm not immortal, I have been alive only 23 years as matter of fact.
Why does it happen to me? Probably because I never use my name,I never meet new people and no one ever calls me by name.
I guess it's just normal to forget useless things, your u don't need trauma to forget.
Oh sometime I forget my own birthday and it takes me a while to remember it, since I only celebrated it once, when I was 6.