Its no big deal, you can always restore your phone via itunes for the "restore upgrade" in a sense. Because no JB is out yet, it cannot be clarified one way or another. But in the past, youd have to upgrade via iTunes for the JB to work properly. Either way, its not like youre doomed, even if you do an OTA upgrade, you can always do a restore via iTunes to resolve this if required by the JB.