Bingo-- here's what I did. I set the timeout on the Mini screen to 5 minutes and just to make sure I didn't keep the screen on because of the screen sharing session I closed that. too. Shortly thereafter, the Interface Disabled messsages reappeared on the iPhone for the Insteon and X10 devices. The minute I reconnected with the Mini the errors disappeared. Just to make sure it had nothiung to do with Screen Sharing I left the connection open. I could see when the screen went blank (I turned off the screen saver) the error messages appeared in Indigo Touch and as soon as I clicked on the blank screen to wake it up they went away.
So we now know what triggeres this behavior but I have no idea why. \