How long have you owned the car? These car have wide wheels on all corners and tend to "track" to the level of the road. When the car pulls ensure that the roads your driving on are pretty "level". Are the tires in good shape or have they been rotated lately?
If you had it aligned the shop that did the work should have checked the related components for wear or slop....but it never hurts to double check their work.....loose jam nuts after alignment jobs are not that uncommon to find. Jack the corners up and check each position for component looseness. Other than that - your power steering rack might be showing signs of needed attention.