I have been seeing this too lately. I would guess it depends on the wording of the contract.
I'd assume since the banks are so busy fielding (sometimes multiple) offers on foreclosures and trying to unload quickly they don't want to waste time if the borrower is unqualified.
If you are working with a buyer's agent, they should have walked through the purchase agreement when you signed it and explained things. You need to try to get your agent to go to bat for you here. If that fails, talk to the listing agent, followed by an attorney if that doesnt solve the problem