"Ah..well there are a couple reasons why I am not sure. First..I died and was dead for 13 years so I'm not sure i am supposed to count those. Which means I can't really do the same as most people and count each year since they have been born. And when I came back to live I wasn't in my own body..this body belongs to someone else and they gave it up for me. And I'm not entirely sure how old they were when they did it..so I could be a different age then the body..and I don't know which one I would go by."

It's a very very complicated life he has led. So he could either ignore the years he was dead and figure out how old he is or he can go with the age of hte body. Both are probably fairly similar numbers but if he counted the years he was dead then he would be in his thirties.