I think they have updated the recipe over the years. It's been out since before Citra was commonly used. I think it used to be more Centennial than anything. Kind of a response to Bell's Two Hearted, like Founders did with Centennial IPA, and Shorts with Humalupalicious.
I haven't had Mad Hatter in a while. I usually find other New Holland beers I want to try instead. They have a whole line of Hatter beers that look interesting.