This is an issue that varies by state. I believe that some states say that it is unethical for a lawyer to draft a will or trust for a client to make a gift to a charity when the lawyer is on the board of the recipient.  Others say it is a conflict of interest that can be waived by both the donor and the charity upon full disclosure.

Even if it is ethical, many firms will shy away from the practice because it is the classic opportunity for “undue influence” and litigation from relatives who think they should have been remembered (or given more) in the estate plan.  If a lawyer is ethically permitted to be in this situation, at the very least there should be other witnesses who can attest to the competence and intent of the donor.  Many will make a video of the signing and have the donor state clearly for the camera that this is truly his or her intent.  It sounds as though this lawyer took very few precautions, but if you are concerned, you should make a further investigation to see if you can find out what really happened.