I encountered grooved surfaces on I-25 and on I-90 on my recent Sturgis trip. Very disconcerting. That induced front end wobble does make ya nervous. I found it seemed to improve a bit with higher speeds and trying to just relax. Seems the Northern tier states have more of this.
I would hate to have to ride 500 miles a day all on this surface.
I saw no signs warning of this in either Colorado, Wyoming or South Dakota.