No, of course not. In fact, Mormons are free to criticize our leaders if we feel they’re not doing their jobs properly.
Take me for example. I’ve repeatedly criticized President Hinckley for allowing our church to be “dumbed down.” This is due to the church bureaucracy’s abandonment of apologetics and refusal to engage our detractors as well as for giving pablum to the members in official church literature instead of creating the means to grow on advanced doctrines.
This criticism does not mean I don’t believe in their legitimacy as leaders - I most certainly do. It just means they’re human, and can and do make mistakes.
What a shocker to anti-Mormons - we Mormons actually believe our leaders are mortal and not inerrant.
Could it be that Hinckley knows Mormon detractors are correct?