It would have to be pretty tilted left to right to pull the tractor to the side. Or, the right side would have to be at a more aggressive angle than the left. I have a Howse disc and, if yours is like mine, it would be difficult to get different angles with the gangs.
If you have used a plow before, then you know how important it is to have the angles right. You may already know the below.
Try this:
>lower the disc slowly, the outside left and outside right side should touch the ground at the same time
>front to rear, the rear gangs should just barely touch ground before the fronts. This is because pulling the disc will cause it to tilt very slightly forward.
>with the disc fully lifted, try spinning the gangs. They should all spin freely. If not, you may have a bad bearing or put the bearings in a bind when the disc was adjusted.
Unworked soil should not affect the tracking of the disc if everything is properly set up.