There seems to be confusion in the comments over facts cleared up in the body text.

The error was mislabeling, which is the most common error in food production. They made perfectly uncontaminated Prawn and Lobster Lasagna and then put the wrong label on it. It should have been caught by quality control at the factory but mistakes happen.

Just earlier this week we had to pull a couple cases of Italian Sausage at work because they were accidentally labeled with a sell by of “Mar 15” instead of “May 15”.