Can't save in campaign?

So, I finally got halo 4 around 3 this afternoon, and instantly jumped into campaign, had 4 great hours of playing, go to take a break, and I get an error saying I can’t save due to not enough space. It asks if I want to save to a different device, I click yes, and it exits the menu instead of providing me an option.

I went to my dashboard, losing 4 hours of content played, and find i have 5.5 gigs of free space, looks like plenty to me for a save file.

I went back to the game, and it still wont save.

Anyone else know what the cause is?