Took this issue to dealer to have repaired, ordered replacement panel and they replaced it but made it worse. They said GM would only replace once. Took it upon myself to remove, rework and re-install. Issue is most predominant in cold weather, when you sit in the front seat and look out over the dash toward the road you see a raised section or sections across the dash panel. I suspect the carrier with the slots in it to support the forward panel is distorting in the colder weather and forcing the panel to buckle or warp. I trimmed the tabs and ribs to secure the panel in a lower position so if it warps it will be lower and hide the condition.