Looking at the manufacturer's maintenance schedule and evidently they call for new plugs every 30k miles. Seems a little early for a modern build, especially considering they come with iridium plugs stock.
Curious as to when you guys changed your plugs and how they looked at that point? I've got a big road trip coming up and if 30k really is the magic number I just might swap them a little early.
Thanks, hope you're having a good holiday weekend.