The Nissan Path

For the last couple days when I get in and start up in the morning, the mpg just has asterisks until I get moving. Then, of course, it starts to slowly trickle its way upward. I also noticed that my maintenance counters all went blank as if they had never been set. I reset them yesterday and they were gone again this morning. For what its worth, it also seems like the "distance to empty" went down rather quickly, but that could all be in my head.
Does anyone have any ideas? I've searched through here and can't find anything, but surely this isn't a first.

Thank you in advance for any ideas.