Hi Melinda -- You should get an extension of the financing contingency period before it expires and while the buyer is still in the mood to sign it. Also, you should start thinking about the possibility that you are going to have to renegotiate the sales price. Most sellers are having to come down to the appraised value in order to keep the contract in force. Most buyers in this market are unwilling to pay the difference in cash between the appraised value and sales price (the way they did 5-6 years ago) in order to get the mortgage (if you choose to hold firm on your sales price). Also, if it's an FHA appraisal, it will stay with the property for, I believe, four months so you're going to have this problem with the next FHA buyer.
It is possible that the home was incorrectly valued, though it is rare for the appraiser to change her work and for the bank underwriters to accept the increased value if she does. Best of luck--I hope it works out for you. Let us know.
Coldwell Banker Residential Real Estate