UPDATE:
It's been about a week since I 're-booted' my '05 FEH by disconnecting the battery for a while (about 1/2 hour) and I thought I'd just post an update.
Everything still works as I expect it should. The EV/ICE and other interactions are as they should be whereas before there was no real rhyme or reason for when I would get the cabin heater pump to turn on when in EV mode and it had stopped forcing the ICE to start up if I set the heater controls in the 'red zone'.
Everything is acting like it should again. I'm working on my first tank of gas since 're-booting' and waiting to see if it helped at all in that area.
Just like with any computer, it's a good idea to re-boot it once in a while. Besides, it gave me an excuse to clean up the battery terminals. Not knowing the vehicle's past history (I bought it last fall w/113K on it) I wonder if the 12V battery has ever been replaced. It looks like it might still be the original Motorcraft battery in it.