listeria concerns have led to thousands of classic hummus containers being part of a voluntary recall , sabra dipping co. said monday .
recalls started after random sample taken by food inspectors in michigan tested positive for listeria on march 30 .
sabra dipping co. said that customers will be refunded if they return the products to stores .
for questions about the recall , call sabra , 9 am to 5 pm , monday through friday at : 888-957-2272 .