A minor point about separation of church and state

The President issued this proclamation, in which he notes the date as:

IN WITNESS WHEREOF, I have hereunto set my hand this first day of May, in the year of our Lord two thousand twelve, and of the Independence of the United States of America the two hundred and thirty-sixth.

Ahem, "our Lord" is not an appropriate usage under a constitutional prohibition against the government favoring one religion over another, right?

Even if this comes out of mere habit and traditions--that this is how proclamations have always been issued--shouldn't the mistake be corrected at some point?

What was the proclamation about, you ask?  It is hilariously tragic and will have you screaming "mayday, mayday!"; read it up here, from where I proceeded to the White House web site.