I agree that it is an appeal to authority, a fallacy.
Actually, it is not, and appeal to authority is not, in itself, a fallacy. The fallacy that you're thinking of is "Argument Ad Verecundiam", which is an Appeal to
Inappropriate Authority (emphasis added). Bolstering your argument by citing an
actual authority on the issue, whether yourself or someone else, is not a fallacy. The fallacy involves citing someone who may be an expert in one field, but not the field at issue.
As an example, let's say you're arguing the original intent of the 2nd Amendment, and you claim it to be an individual right, citing the Federalist Papers and perhaps recent SCOTUS opinions. Your opponent responds that Albert Einstein and 10 of the world's most prominent physicists agree (
agreed in the case of Einstein, of course) that the 2nd was intended to apply only to militias. You're on solid ground, because the framers and SCOTUS justices (arguably, in some cases, perhaps) are in fact experts on the issue. Your opponent has committed an
argument ad verecundiam by appealing to authorities in a different field.
Reference: Copi, I.M and C. Cohen. 1998.
Introduction to Logic, 10th ed. Prentice Hall, Upper Saddle River, NJ. 714 p.