I deleted my membership in the company of friends in my old location and got the email below.  Unless removing yourself from a group is considered inappriopriate behavior ;-), this is a bug. 

You have been removed from the XXX XXXXX - Company of Friends group due to activity that is deemed

inappropriate for the group and/or for Fast Company. As the group moderator,

your membership may be reactiviated at my discretion.

For a list of Fast Company guidelines and regulations, please follow the link below:

http://beta.fastcompany.com/guidelines

Thanks,

Fast Company Staff