I was unable to reproduce this in single player or on the server via a variety of mining methods.
I'm going to close this as it's a not very severe mod issue and there's not much we can do to fix it. I would suggest relaying this to the mod devs via their Discord and/or issues page on GitHub. Please open a new ticket if you think this is a mistake, or if you know of a fix we can implement.
If for whatever reason you continue to have this issue and need fans removed, feel free to ask me to remove them via discord or via a new ticket.