Rented a movie from ITunes, and it's saying I don't have enough storage

I just recently got an iPad (4th generation) and I've recently rented two movies off of iTunes, and they loaded and worked perfectly fine. Ever since then I haven't downloaded any new apps, or made any changes to my iPad. Just tonight, I rented ONE movie, and it won't let me download it now cause I apparently don't have enough storage?? Like I said earlier, I rented TWO movies and was able to watch them, and haven't downloaded or made any chances to my iPad to make the usage of it change.