911s front brake rebuilt

I have a 1970 911s with aluminium front brake calipers.
I recently had the right front caliper rebuilt since it was "hanging up" causing the car to pull to the right when braking. The brakes now work but have a soft spongy feel to the brake pedal. The shop which did the work said that this is normal and should correct itself in about 500 miles.
I am puzzled by this since about 5years ago I had the left front caliper rebuilt and didnt have this issue. That work was done by another shop which sadly
closed/retired.

Does anyone on the forum have any ideas/thoughts about this?
Am I being fed a load of nonsense and if so what is the solution?
I would be very greatful for any ideas.
Thanks

My brakes were a little spongy after I rebuilt my brakes. It took about 100 miles for them to firm up. Supposedly the new dust seals on the caliper pull the piston back further than broken-in ones, thus it takes a little more pedal travel to get the same feel.

If it doesn't improve, bleed the brakes again, that should do the trick.