I was just looking at the front brake pads today (at around 3400miles) and couldn't see the thickness. I recall being able to see them when I got my car at 6 miles.

So I looked at the rear tires and I can see the rear brake pads without a problem.

Was I hallucinating earlier on when I thought I was able to see the thickness of the brake pads? Or is this normal? ie. front pads are smaller than the rear and therefore cannot be seen? Or are my front pads already worn down and needs replacing soon?

I've done nothing but mostly highway driving. Can't imagine why I need to change the pads so soon?

 

Don't worry, if they are the stock pads, there is a pad thickness warning on it. A little metal arm will scrape at the disc when you are almost out of pad material, giving out a loud "SCREEEEECH" sound. When you hear that, then it's time to replace your pad.