TurbineTolero took to the forums to clarify the issue:
This impacted a limited number of players after the maintenance work, and we have a list of the affected users. We're working with our partners to make sure that over charges are reversed. You do not need to contact us to receive help, but if you have any questions you are welcome to call or send a ticket (phone is 1-855-WBGAMES and tickets contact can be done via http://support.turbine.com).Our sympathies extend to those affected more than passingly by the bug.
[Thanks to Marc for the tip!]