Private sector work. 6 year project with 3 years already complete. Owner does not withhold retainage from their GC. We are a sub to the GC. The GC recently started holding 10% retainage. Our contract with GC has a clause that says they can withold retainage but they have done so for the first 3 years. Can GC withold retainage from their sub if the owner is not witholding retainage from the GC?