I understand, but you're still creating an entirely new entity; an LLC is in no way similar to a corporation.
Further, you're still filing articles of incorporation (at least in a sense) using the CA procedure and changing your LLC (which, as far as the IRS is concerned, defaults to a disregarded entity or a partnership) to a corporate entity. The only variable here is that you apparently made an S corporation election (Form 2553) for your LLC.
Frankly, whatever the agent told you on the phone cannot be used as any sort of authority so you might want to at least get something in writing to that effect. I'm just not sure why erring on the side of caution and getting a new EIN is not the better course of action.
