It was just a phase that the Doctor went through in his youth.I didn't just didn't mention it. But does anyone find it's weird that at the end of T Bakers era, he suddenly randomly adopts question marks, wears them through out his 5th and 6th life, than wears them for a god chunk of his 7th incarnation before randomly scrapping them, and ever since he has never so much are looked at a question mark?You also forget that DURING the Seventh Doctor's lifespan he abandoned the question marks. There's none to be found in The Enemy Within.
