wheels off center after differential work

[Benz300]

My car was at the mech. for replacement of worn differential mounts and also the replacement of one of the rear control arms at both rear ends.
after i picked up the car today i noticed that the wheels are not in the center of the wheel wells anymore. they're almost 3.5 inches towards the front of the car. which looks strange.
i called the shop and they said it's normal as the new control arms and bushings are pushing the wheels/diff towards the front of the car.
that doesnt sound right to me. after all if that was the case the wheels should've been off center like this even when the car was new.
can anyone provide some input.
thnx.