The module doesn't clean up the it's field data in the database when it is uninstalled.

Comments

Status:Active» Closed (works as designed)

This is up to core, AFAIK this module doesn't need to do anything special about it. You will find issues about this in the Drupal core issue queue.

The message module has code in its uninstall to clean up the field instance it creates.

Status:Closed (works as designed)» Active

Oh sorry, I miss read the project name, and thought it was Message.

Status:Active» Fixed

Fixed.

Status:Fixed» Closed (fixed)

Automatically closed -- issue fixed for 2 weeks with no activity.