Replacing just the pins won't cure the problem, you need new boots as well.
Here;s a list of part numbers you need
Part numbers for fronts:
2 x 47715-22070 Pin, Cylinder Slide
2 x 47715-30060 Pin, Cylinder Slide
2 x 47769-50010 Bush, Cylinder Slide
2 x 47775-30070 Bush Dust
Also there is a guide here on how it should be done.
http://www.lexusownersclub.co.uk/forum/tutorials/article/161-caliper-slide-pin-overhaul-plus-all-models-i-think/
Highly unlikely that your guy did the above.