Products being recalled depends on many reasons and on what type of product it is. From what I can tell you from previous experience, is that that product may not have been for every single test possible. While I was interning at Prosidyan this summer, they have had to recall some of its lots due to extreme heat issues. Prosidyan makes bone graft substitutes products in the form such as morsels and putty. When these products got realised, there was no issues. But they had a complaint from one customer saying that they product has been melted. When we did some research, we have found that no one has picked up the delivery and had been sitting out in the sun in the packaging. This was never an issue till now because this factor has not been tested. That is why some of the lots of the product have been recalled.