Have you opened a support ticket for this? I am pretty sure I saw a discussion of this internally. If not, could you share the performance workbook view of the queries? I believe these were showing multiple queries running concurrently but that may have been a different customer.
In addition, please open a ticket with support if you do not have a current ticket open.
Thanks for your response. I haven't created a support ticket yet, but will do so now. I was just wondering if other people had experienced this behaviour.