iPhoto Update Through Mac App Store Problem

EDIT: Never mind, signing out and in on the MAS seemed to do the trick.

I cannot seem to install the latest update to iPhoto under the Mountain Lion GM. I didn't purchase the app through the store, instead it came pre-loaded as part of iLife '11. When I click 'Update' the store just hangs on the 'Waiting...' stage of the update. Anyone else had this problem, or a fix? FYI I am running a legit GM.