Not that I'm going over March Break, but just out of curiousity I checked MCO-BUF March 17th about 15 seconds after the fares were released. The $59 fares were NEVER made available.
But check them daily, since they may open up.
Example: MCO-BUF Jan 6 fares dropped to $59. Within hours, all the $59 fares were not available. Several days later, one flight MCO-BUF $59 became available again for about a day. So yes, even after showing unavailable, fares sometimes do open back up. But if several fare categories on a particular flight are showing unavailable, I would be VERY surprised if they opened back up.