Around 3:30, I woke up, realizing that Lisa hadn't gotten any sleep at all. The shower compartment on our refurbished Superliner is a separate module that replaced the older shower compartment, and it's made of a lighter weight plastic than the original.
One of the reasons I woke up was that we were stopped in Salt Lake City. There is indeed a huge amount of schedule recovery here. Despite being roughly 30 minutes late all the way from California, we arrived at SLC more than 45 minutes before our scheduled 4:20 departure. With the train stopped, the squeak quit as well, and Lisa climbed back into bed to try and get to sleep before we got moving again.