CA Prob Code Section 21388

(a)

A person is not liable for transferring property pursuant to an instrument that is subject to the presumption created under this part, unless the person is served with notice, prior to transferring the property, that the instrument has been contested under this part.

(b)

A person who is served with notice that an instrument has been contested under this part is not liable for failing to transfer property pursuant to the instrument, unless the person is served with notice that the validity of the transfer has been conclusively determined by a court.