If you sign documents in Maryland, then you move to another state, are they still OK as-is?
Because of the full faith and credit clause of the United States Constitution, documents produced under the laws of one State, are presumed to be effective in any other State. That is only a partial answer, however.
The better advice is that, whenever you move and establish legal residence in a different State (or other jurisdiction), it is strongly recommended that you have all your existing legal documents reviewed by a good elder law and estate planning attorney in the new State. This is because each State has its own laws regarding each of your important legal documents (e.g., Advance Directive, durable Power of Attorney), Last Will & Testament, Revocable Living Trust) .