Galaxy Nexus 4.1 OTA: disappearing update file!

Just purchased a Galaxy Nexus. After updating to 4.0.4, I went to the "system updates" menu screen and saw that the Jelly Bean OTA update was downloading. When it finished, I pressed the "Restart and Install" button. To my absolute shock, the update failed to install, and instead, the menu told me that my phone was now up to date, even though the Jelly Bean update downloaded but never installed. Now I can't get it to download the update again, nor does it prompt me to install the update. Because I used custom ROMs on my last phone, I really don't have a feel for how OTAs work. Is the phone going to prompt me in a few days to update, or is it broken somehow? And has anyone experienced the same issue?