Did i do the wrong thing? (car-related)?

alright so i just got my G2 a little while ago and im a very responsible driver. i was driving my friend home today and i pulled into her drive way. when i was backing out and just about to put it in drive again to leave, this crazy car comes speeding up the street, blaring music, with no intention of moving out of the way. he wouldve sideswipped me (at the very least!) so i straightened my car out to move out of the way. though, in the panic of doing this, though i did it very slowly (2km/h) i accidentally touched the car behind me. i got out and looked but there was no damage to the car and nobody around to talk to. i didnt leave a note because there was no damage. did i do the wrong thing?