Guys, insist that your wheel is straight after an alignment. Tell the shop your test driving it around the block. If it's out ask them to fix it, politely but then and there.
It is very common with Subies that this happens. I have had more than 20 wheel alignments done on my WRX and most times the wheel needs readjusting. I put this down to some hysteresis in the steering box. Some might call it "Slop"
Shane at Exley's in Willeton has done more than his share of WRX's and will tweek your wheel straight if you let him know. Likewise all the other shops, however if your to lazy to tell them you get what you ask for.