Matt and I were having a discussion just the other day about how some people have no idea how to use the "best if used by" or "sell by" dates on food. I know people who will throw out perfectly good food just because today's date is one day beyond the "best if used by" date.
No. Food can be good for many weeks beyond the "best if used by" or "sell by" dates. Industry probably relies on the confusion around these dates to sell more food products.
My rule of thumb is this: if it looks good, smells good and tastes good then it is still good. Modern refrigeration can keep food fresh for weeks! I think common sense is in order.
You can read more about what these dates really mean here.