Courts in most states hold the Attorney-in-Fact (the person granted the powers under the document) in a fiduciary capacity — in other words, the attorney-in-fact owes the person who gave the power of attorney (the grantor) a fiduciary duty.
The Attorney-in-Fact owes the grantor of the power a high duty of good faith, fair dealing, honest performance, and strict accountability.
As such, the law may (in certain circumstances) imply an obligation to provide notice to the grantor when the attorney-in-fact makes decisions on behalf of that grantor.
That being the case, the question then becomes, “Why not notify the grantor?” A simple email or note to the grantor outlining the steps being taken on his or her behalf shows full transparency in the conduct of business under the Power of Attorney designation.