Drupal - Entity Tokens + Date Field + Custom Format... unable to use spaces

In this commit to Date module, token integration was removed, because field tokens aren't working yet.

The error you got it reproducible with an older copy of Date module, but doesn't seem to be related at all to Automatic Nodetitles, just Date/Token.

I would wait until the above Token issue and the Date issue Re-Add Field Token Support are committed.

This is actually a core bug that spaces cannot be used in 'dynamic' tokens. You may want to try the patches available in http://drupal.org/node/1035292.