well I called the dealer and they told me it had to do with the colder weather which I kinda already new. they told me when it's cold I should just pump them up 2-3 psi more than it says on the door. they did of course offer to take a look to make sure it's not a faulty sensor once I bring it in for my first oil change.

I just find it odd that it only happens on the highway and it doesn't remain on...longest it has stayed on is 5 minutes.

I appreciate the replies from all

 

Nitrogen will have less fluctuation than air but both will fluctuate some. Happens in my Charger every year, normal.

 

yup most likely the cold!

 

This will happen just about every fall as the cold weather sets in. It's pretty annoying, but I guess has some value.

As for nitrogen fill, I certainly wouldn't pay for it. After all, the good old stuff that we breath every day is 80% nitrogen.