My 1 year old walks on her tip toes too. I think its pretty normal, they are however still learning to walk. Also, my 8-year-old niece walks on her tip toes all the time and she is absolutely fine, no autism or anything. Everybody's different! If he isn't showing signs of autism, and trying to talk then I wouldn't worry. My cousin's 8-year-old son is autistic, and he's still not talking, so I wouldn't worry.