Often, that stress is sufficient to trigger a slide. Stay to one side or find a safe spot, but keep an eye on the stuck snowmobiler. Highmarking inherently involves being on steep slopes with potential avalanche hazard, so if you are inclined to play this game often it would be a good idea to learn more about stability analysis. Whether highmarking or not, consider your route carefully. The side of ridges facing the winds are typically scoured, hardpacked, and safe, while the lee sides are often loaded with all the snow.
Cornices usually indicate that the slopes below are or have been loaded by the wind.