Josh, I know you use a Mac but it shouldn't make any difference. I recently had exactly the same problem with my iPF5000 for no reason that I could think of. Eventually, by trial and error, I checked the printer properties in Control Panel and found that the Device Settings tab had a checkbox for the roll feed unit that needed checking. Once checked the problem was solved. Perhaps this is your problem? I have no idea how that box became "unchecked" but there you go - things happen.
Cheers, Bob.