Hi scottg,
Welcome to the SEBLOD forums.
What do you mean by "disappeared from my template".
The Article Content Type is a skeleton "template". So if the Article
Content Type is changed, and a new Content Type is created based on the
Article, the changes will be reflected in the new Content Type.
My guess is that the field was inadvertently removed - I have never heard of any issues like this. If you continue to see a problem, then try to document the steps and let us know. It is also good practice to make frequent site back ups.
thanks,
Randy