George, you're killin' me.  Is there anyone on the planet who would even THINK about worrying about a copyright problem with a plat book THAT WAS PURCHASED decades ago?  No.  There isn't.  I own the book.  I can do whatever I want with it.  It's not like it was stolen by my grandfather.  He purchased it.  Michigan sells platbooks to anyone who wants one.

 Should I worry that giving away books to Goodwill is a copyright infringement?