Yes - this is the type of unfortunate mistake that one would expect if serviced by someone not familiar with Patek. In my case I was told the PT950 Ellipse has a special case back with special tools needed hence it had to go to Geneva. And yet I suspect the mistake was made at Geneva and the "special tool" markings remain on my case as a reminder.
Sorry to hear this has put you off from enjoying the 5119. I have the same disappointment but for now will try not to look at the case back.