Where had they been? If they were in the freezer since before July 31, then they are perfectly fine. If they had been in an unopened package in the refrigerator and just got opened today, then they are at least borderline fine. Where I would worry is if the package had been open since before July 31. No matter what the expiration date is, once you open a package of meat, you want to use it within seven days. If the remaining ones looked OK and smelled OK, then you are probably all right. Most of the time it takes something pretty bad to make people sick.

Doug