Problems with buyers after closing of escrow

We recently sold our house and closed escrow. Just before the closing of escrow a plumbing problem with the main pipe arose. We disclosed this problem to the buyers and got an estimate from a plumber for replacing the entire pipe. We wrote a contract stating that we will pay for the replacement of the pipe but also that we will not be responsible for any other existing or future problems. We added that the responsiblity includes but is not limited to financial responsiblity and responsibility for additional costs/fees incurred. Both us and the buyers signed this document as a way of showing acceptance of the terms stated in the document.

Now about a week after escrow has closed, the buyer's real eastate agent contacted us and notified us that replacing the pipe is going to be more than the plumbing company's estimate and that the buyers are thinking of taking legal action if we're are not welling to pay for the extra costs. Do these buyers have any kind of legal case against us? If they do or don't, what do I need to do from here on to protect myself.

[HomeGuru]

You need to have an attorney review your contracts because if you wrote the contracts yourself, the language used may not afford you the proper protection.
In addition, there is the State disclosure laws that may apply.