My owners manual says I need to change the top row of plugs on my 4.7L engine at 36 months or 48,000 miles.

I just changed the oil and filter at 36 months and did my normal crawl-around-under-my-truck inspection to make sure everything is still attached. Everything looks good.

My truck only has 9058 miles on it. Do I really need to change the plugs? I know they will still look like new and it won't change the performance any but will I have any warranty issues if I postpone the plug replacement for a while?

My track record is spotty when I have replaced things that didn't need replacing. Too often I break something.