[Quicksilver]

If the tires are unevenly worn it can pull in one direction. If the alignment was off it could have worn the tires that way.
Other things to look at are:
- Is there is crown to the road it will cause the car to pull?
- Are the tire pressures uneven?
- Do both front wheels spin freely and evenly?

If this doesn't explain what you are seeing then either the alignment is off or very likely-> the corner balance is off.

You can swap the tires left to right to see how that effects the pull as that would reverse the effect. Make sure the tires are evenly inflated and find a really flat chunk of asphalt to test it on.