I've had that happen before, I think mine was because the axle got all twisted in the clamps and made the forks bind up. Have you ever taken your front wheel off and put it back on and it not be straight because you tightened it down in the wrong sequence ? Once I loosened my triple clamps up and took the front wheel and axle bolt off for inspection, just put it back together and if it goes straight your good... if not, you probably got a bent tube or triple clamp.