I had a friend who called me this morning about this. He was watching G4 and they were reporting on the Wii's that were DOA. There was also a lot of Wiis that prompted you to insert a startup disc when you powered them on. Apparently, these were display models that accidentally got sold along with the regular Wii's (the startup discs were sent separately to the stores as a theft prevention measure).
Turn G4 on if you can - maybe you'll find out more there. I know this doesn't help you, but I say you shouldn't worry about it - your Wii will either work or not work regardless of how much time you spend worrying about it.
