I agree. All the pre-Hogwarts magic he does is his subconscious reacting to the world around him (hair growing, sweater shrinking, getting to the top of the school building and glass disappearing). Shame, shame, fear and anger, respectively. But I am not sure I would tie it too closely to the teen rage Harry, although it is true he does have an anger management problem (I see that more in how he acts in class) -- this is after all not his conscious action.

I was semi-joking at first, but after thinking it through some more, I think this initial book does set up where some of his anger in the latter books comes from. Not necessarily a tie to the subconscious magic when he was coming into his powers, but his treatment (and abuse) by the Dursleys does spur some of his more violent reactions.

Blowing up Marge, again subconsiously in PoA, was in a fit of rage at her comments about his parents. Most of his anger and resentment in Order of the Phoenix seems to come from treatment that resembles what the Dursleys had done to him all along; ignoring him, trying to keep him in the dark about everything, and a feeling that people undervalued him.