That doesn't surprise me. I am building a house and the sub-contractor shenanigans are REALLY starting to piss me off.
They know you are on a schedule and paying interest through the nose for the construction loan, so they bide their time and then announce the week before they are to start work that their costs have increased and they can't honor the bids they made.
The worst was a guy who raised his price for some natural stone veneer by 50%, and tried to pass it off as due to increases in the price of gasoline.
They have you over a barrel. Either you tell them to go to hell, and accept the expense and delay of getting new bids, or you grit your teeth and pay the filthy liars.
I am very, very dismayed at the lack of honesty and integrity in the construction business.
Never hire white guys. South Texas rule.