I haven't received such mail. But this is probably coming from the billing department, and the person managing the month-end-statements may not have thought about it much. Sounds to me that it is a standard statement, and i really don't see a need for them to expound on the issue. Most customers would accept the brief explanation. Shareholders may be more sensitive because of the SP movement.
i got an email with an invoice much later than normal. I think it showed that I paid it though, but it was unusual that I received it when I did weeks after my order was completed.
and on a different subject I also ordered 4 bottles and 2 balms and they only sent me 1 bottle and 1 balm. I called them and they quickly fixed it and sent me out the missing bottles without even questioning me. I thought the customer service was just fine.