That is why there is now a clear button :)
Honestly I switched back to prepopulate it because I found it tiresome to have to insert the episode name each time I wanted to check in. As you said, originally I made the decision to leave the field clear to encourage users to compose their own messages.
I think I'll post on Google+ about this to ask around a little what is preferred. I'm not really sure what the best default is here.
Uwe