I don't know if it's bad. That was the recommendation from the shop to replace it but I haven't been able to find any articles or info about the separator going bad. If it was due to the cold weather then replacing the cover isn't going to matter, unless they've updated the design.

I had oil in a couple of my spark plug wells when I recently did the 100k service so I believe it would be a good idea to at least replace the gaskets and seals, especially after this happened.