Why don't you take it to your Lexus dealership and have them hook it up to their computer before you spend money on a guess?

 

The car's efficiency and performance aren't affected so I doubt plugging it in will give them much info. I didn't even notice any of these issues until after I got it home, and given that I only have one Lexus dealer with a good wait for a service loaner, I figured it was better to educate myself on the possibilities rather than let them stab around all over eating up diagnosis time.