Fulfill Drop Ship Item?

I need help understanding something that seems to be happening more and more for us.  I create a Sales Order for qty 1 of Part A, and qty 1 of Part B.  Part A is in stock, while Part B is not.  At the same time, I select to have Part B drop shipped.  When I save the Sales Order, a Purchase Order is created for Part B, as expected.

However, when our warehouse goes to fulfill this sales order, it allows them to fulfill both Part A, and Part B!  The Picking Ticket only shows Part A, like it should.  (Unfortunately our warehouse personnel sometimes don't read the screen very well and just fulfill everything because they assume it's correct).  Should both items even be listed to be fulfilled?  I don't believe this use to happen, but I cannot be sure.  The Purchase Order does have the "Mark Shipped" button, as it should.