I always have fastboot turned off so if I need to boot into CWM I don't need to pull the battery.
After I factory reset the syncing problem was solved and after upgrading to the latest official rom, now my phone restarts normally with out any updating message.
I think it might have to do with the flashing of gapps. For some reason, I think, the old version of the play store keeps wanting to reload itself.
Just something to test: Turn off fast boot / turn phone on and launch play store with out any data or wifi connection. It obviously wont start properly because you're not connected but look at the top bar and see if it's the old version of the play store.
Also did you notice this after you installed gapps or before?