Bluedonk, it sound more like a uncentered nose wheel steering, as in you may have centered the tiller, but didn't allow for enough time for the nose gear to drive back to center. Was in a rolling takeoff after a 90 deg lineup? Maybe little uphill during the turn with 40% already set, immediately when lined up toga-push?
Been there, done that. Took full rudder pedal and some tiller to keep it from going off to the side. Was close to rejecting too. Been extra careful since, to ALWAYS allow the aircraft to roll straight for some meters, AFTER releasing the tiller (to ensure the nose gear is in the same position commanded by the tiller), before pressing toga.