Maybe your indy has replaced the control arm and depending on which control arm, he may have had to first remove other control arms or suspension links and then all the bolts were tensioned with the wheels hanging??

When the car is then lowered back to earth, all the bushes are under tension and not in their natural centre position, this will effect the rear steering geometry.

So under braking the rear of most cars tend to rise and the front will dip, if you have differing rates of control arm torsions on either side, it will cause excessive toe on one side and cause the rear to steer one way.

Have your indie back off all rear control arms, with the car over a pit or on a four post and then bounce the car a few times (I usually open the boot and get a few guys to sit in and bounce) and then tension all bolts.

You also need to have the rear wheel alignment checked.