Hokiegreers

I have a 2015 Yukon Denali XL 2wd with about 97K miles. Recently I started getting a intermittent vibration that sounds like a growl and sort of feels like you are driving over the wake-up strips on the side of the highway. The truck seems to be driving fine. At first it didn't happen very often and the duration was only a couple of seconds. Now it is happening more frequently and the duration is lasting longer. Any ideas would be greatly appreciated.