Restart your iPod (Home + power buttom) then try again. If that doesn't work, backup your iPod then restore it..
I have rebooted several times since the update, haven't had a backup complete yet (would have yesterday, but I broke out of it to shoot for a Prairie Chute code ) Backup is gonna take about 2.5 hours by my estimation...
Well whenn was your last backup? Because if it was like 5 days ago and it doesn't matter to you if you loose some saved game data...It's all up to you.
Last backup was two days ago. Only thing I'd really miss in restoring is some of the achievements in Ramp Champ...