I've recently started a new career with 1.3 and the current version of Galileo Planet Pack. After a few missions, I noticed Bill had disappeared from the roster. Which was weird, because up to this point, he hadn't even seen the inside of a capsule. Then I looked at an available tourist mission that I've been ignoring, and there he was. I never authorized this vacation, so I went into the save file and replaced every instance of "Bill" with "Gill", and copied Bill's data from a fresh save file. This seemed so set things right. No harm done.
A little later, I noticed Bill had gone missing again. This time I found him in a rescue contract I had already accepted. So I rescued him, and now he's a scientist rather than an engineer. Again no real harm done.
While this hasn't seriously affected game play, I am curious why it's happening and if I can stop it. I don't know if it's a KSP issue or an issue with something I installed with the Galileo Planet Pack. I don't want to have to worry about assigned crew disappearing from missions to go on vacation or need rescuing from half way across the solar system.