Alignment Question

After buying a new set of tires for my 98 Buick Regal, I took it to Brake Masters for an alignment. Before the alignment, when I hold my steering wheel perfectly straight (I try my best visually) the car tracks straight, even when letting go of the steering wheel. But after the alignment, I noticed the car leans right when holding the steering wheel straight, and in order to go straight, I have to pull the steering wheel slightly towards the left about 3-5 degrees, although, at this angle, the car doesn't seem to pull to any direction when I let go of the steering wheel. When I asked the technician at Brake Masters, they gave me various technical explanations of how every car and type of tires will have different alignment results etc, etc. And that the steering wheel will not always be perfectly straight. Now, since this alignment was done on a computer-laser machine, am I being jerked around? Thanks for any input.