According to the USDA some salad sold at Trader Joe's could be contaminated with Listeria. 

The alert only affects the broccoli slaw and kale salad with chicken. There is no recall however, because all of the salads are believed to be past their "use-by-dates" meaning they are no longer sold. 

If you still have either of these salads at home and they have expired, make sure you throw them out.