Nope. MIT licence means you can do what you want with the thing as long as you keep the initial blurb in. Up to and including adding your own restrictions on access.
Edit: Case in point, it'd certainly be *nice*, and definitely encouraged if you threw back any fixes for flaws you run across, but strictly legally speaking, you aren't *required* to do so. Just slows down getting yet more goodies since folks have to independently find and fix em themselves instead of looking into other things.