Because there were a lot of tornadoes that caused a lot of people to lose their homes in the southern US about a week before the air date. They thought it would be a bit tasteless to show hurricane episodes in the immediate aftermath of what happened. The episodes will be aired in the next season of each show.
http://en.wikipedia.org/wiki/April_25%E2%80%9328,_2011_tornado_outbreak
http://en.wikipedia.org/wiki/Seahorse_Seashell_Party
http://en.wikipedia.org/wiki/Hurricane!
http://en.wikipedia.org/wiki/The_Hurricane!