a few thousand worth it to maintain a happy customer who knows that they can count on you, yes?
in construction in texas, if you are sticking to the schedule and accelerated deadlines are made, premiums are paid where necessary. sometimes T&M basis, sometimes bid/execute, not saying it happens with DPDW, but for concrete work it's always a negotiable point if you are sticking to the plan made during contract negotiation.
anyone who bids a job learns early on, you ahhhh pad a bit for for the un-forseen. Keep in mind now that you dont want to loose a contract because your to high$.
IMO my favorite vendors, regardless of the cost (who I steered work to) were the guys who got it for me yesterday!