My 3yr old son changed his name to Kobe

When he comes home from preschool he changes into sweat pants, t-shirt, warm up jacket and to top it off, some JORDAN'S! He told us his name is Kobe. I just called him by his birth name a few seconds ago and he did not answer, few minutes later I called him again, only to hear a little tough voice say: " Thas not my name!"