I think you can work around this issue for now by saving the “shaky” model to a NEW file name; shutting down Rhino and the restarting/loading the new file.
You are probably not using SR12 since we just released our first release candidate for it this week. I just checked and the fix that I made won’t be available until next Tuesday, sorry.
You can check to see what version you are using by looking at the help->about screen or by running the SystemInfo command.
Here is information on getting the SR12 release candidate. Again, this specific fix will probably not show up until next week.