I'm with Lawrence on this...if a customer came in and told me that I had to go above and beyond what I've already agreed to in the signed contract....I'd be asking them for a change to the contract that involves some money to cover the extra testing.
Funny thing is that I macro-etch my welder's coupons because they are always curious how their tests look and are usually amazed at the detail that the etching shows...but....What I don't have, is that testing noted in my welder's quals, just the side bends. There is enough material left over and it only takes a few minutes to polish and etch a couple cuts.