I just rebooked a flight about an hour ago, and got an error upon check out. My itinerary seems to have changed, but I didn't get an e-mail conf/receipt and the online receipt doesn't reflect the new ticket (has old flights and says EXCH). Am about to call them to see if it is good on their end (most likely not). I'm also now having issues logging into the website, but the app works fine.
Seems like something might be funky somewhere...
Edit: Seems like the website might be a cache issue...tried another browser and it works.