Nifty necro! I was just thinking about this post yesterday as a matter of fact! I'm going to keep this post up to date as the new novels roll out. I still mean to go back and track the changes to Murphey's name. Harry changes her name as their relationship changes, and you especially notice it in the later books when (coincidence?) Murphey's character changes quite a bit.
If anyone wants to help me out, I want to track the book numbers where it changes. I think she was Murphey originally, then became Murph as they got closer. And towards the end he called her Karrin a lot. That's all from memory though, and I want to track it down to be sure.
I remember at one point reading a WOJ commenting on a reader's observation about the nickname changing after that business in changes. He said something along the line of "I love an observant reader."