It may be possible the "servicer" for the actual investor on the mortgage wants you to pull your offer so they can get financial incentives under the new HAFA short sale program. The investor that owns the mortgage and the Mortgage Insurance company may also get incentives under the TARP HAFA program.
Worth a try...
If you rescind your offer, the seller is free to look at any other offer and subnit it to the bank.
Do you know how far the home is from foreclosure and how long the process will take?