A bad habit picked up by the Eleventh
When he was hanging around with Stan Laurel.....
We never saw the Doctor physically make contact with the boy, but it may have happened.
The moment of contact probably occurred in the edit between his first sprint upon hearing Rosita's cry for the Doctor to the shot where he was running down the alleyway. The lad had wandered off just before that but had to be in the general vicinity in which the Doctor was running. So he would have been in the way and thus the Doctor had to nudge him aside.
I'm going to make the claim that the unnamed lad would grow up to be Jim Taylor, a character from the TV adaptation of Philip Pullman's "Ruby In The Smoke".
Have no fear, the Toobmeister is here with a splainin. During the rampant destruction caused by the giant Cyberman (which somehow must have been covered up by the Torchwood Institute), the lad - that is, Jim Taylor - was seriously injured. He recovered, to the point you would never have known he had been in that disaster, but he was never going to look as he did as a young boy again.