User getting approval error when posting receivings

[mebenz]

A user is setup with unlimited approval authority. She receives (shipment/invoice) a bunch of POs and when posting, some of them give an error "Purchase Order has exceeded your approval authority amount, it will be saved with a status of unapproved."

First of all, this PO had already been approved (ie you can't receive an unapproved PO). Why is it even looking at a user's approval authority when posting a receipt? The user has unlimited authority.