2018 CTS-V vibration

I have noticed on both of my CTS-V's that while on the highway I feel a slight vibration. One of them was a 2017 and this one is a 2018. While driving on the highway with foot slightly accelerating I feel a fast slight vibration. It happens every 3-5 seconds and last for about a second or two. I never hear it but feel it, it almost feels like very small wake up bumps that are on the edge of lanes. The vibration has that pattern to it but on a much smaller scale. I hope I am explaining this well. Anyone else have this going on or know what it could be?

Thanks in advance