Regardless of what the shop did, a good master cyl should tolerate full stroke. Rebuilt masters usually have a pretty rough bore, this leads to rapid seal wear. Wet fluid can corrode the bore pretty rapidly causing the same effect.

Changing the fluid is sometimes a short term fix, ( new fluid has fresh seal swelling additives )

If the hoses don't leak, they are not the cause of the problem.

Don't drive the car, change the master cyl.