No. Like the other poster posted, if it's 51% tequila, it can still be called tequila. So long as it is in Jalisco (for the most part, I think there are a few exceptions) and has a NOM and is approved by the Mexican government, it can be called tequila. 51% is the minimum amount that it can be and still called tequila.
But like I said, it's the same as making a spirit 51% bourbon and 49% filler and calling it bourbon just because the government says it's OK.
So, if I have this right, it's not at all shocking that it's called "Tequila"?
"Every bottle is its own learning experience." -- Sensei Ox-sama