My neice is twelve and her shoe size is 10. She is also taller than me. I'm 5'6". Its totally normal though. I was my full height and shoe size at her age as well. KIds are just developing faster than they did in the past.
Of course it's normal. Kids grow at different rates. I'm nearly thirteen (I know I'm not supposed to be on the site, but this is the Internet) and I wear a size three. I haven't grown since I was ten. We're all just different.