Harri Larkin - Design Changes

I recently posted about transferring the files for Harri Larkin's band logo to the band and the difficulties that arose in doing that. I had assumed that when they said they were happy with the designs that it would've been the end of the logo project - hence why I spent so much time preparing the files for them. However they got back to me a couple of days ago with some feedback and wanted some fairly big changes doing. Whilst this isn't a major inconvenience for me at the moment, it certainly highlights the importance of the signing-off process when dealing with clients, something which I didn't deem this project big enough or serious enough to need, especially given that I'm doing this project for free.