Just joined so I can add another data point...
I got this message today in my 2015 85D that has expired warranty. I submitted a service request and got the sticker shock for $942.11 ($640.50 labor, $239.98 parts, and $61.63 tax). The audacity for Tesla to charge $305/hr for labor, but that's a topic of discussion for another day!
Needless to say, I'm ticked off as I don't see this as a wear-and-tear item, so warranty shouldn't even come into play. In my view, this is a safety issue and should be handled via a recall. I also don't think it's a coincidence I received the error message AFTER my warranty expired. For now, I am opting to postpone any service. I do plan on filing a complaint with NHTSA.