hook_product_cart_remove_item not being called when items are removed from the cart

In the shopping cart view (i.e. - http://www.mysite.com/cart/view) clicking on the remove link to the right of the product doesn't seem to fire hook_product_cart_remove_item. I believe I've tracked the problem back to the ec_cart_update function in which several references to $items[$nid] appear (around lines 888 - 891). I've tried locating the declaration for $items but I'm beginning to suspect that $items[$nid] should actually be $item. However I'm not terribly familiar with the workings of the ecommerce module so I would not be much surprised if I were in error.