For some reason, a hiccup with my internet just as I was trying to save one of my sheets gave me the good ol' 'Error logging into sheets system' message, and now I can't save the changes I was making to the sheet because it doesn't know it's me trying to do them (aka I get a 401 error.)
In practice I was only changing like two boxes so it's not like it's a big deal to just do them again, but it would be nice to be able to authenticate with the sheet system without having to leave an open sheet.
EDIT: Remembered the JSON downloader exists and that downloads the current state of the sheet and not its saved state, so that's an easy solution. Still would be nice to have a login button on the sheets.