It was saran wrapped. I should have known better, but didn't want to buy an entire shoulder and grind it for a small batch. I haven't bought ground beef or ground pork from a grocery store in over 2 years. I prefer to grind my own so I know how fresh it is and what I'm getting. I may try again with some fresh ground pork and beef.
Do you hand mix or use a mixer? Could be the meat got to warm, mixed to long. Try to keep the meat cold. Use a double bowl, bottom bowl with ice with the meat bowl sitting in the bottom ice bowl.
Nothing wrong with using store bought meat, just look for the meat to fat ratio. Most of use here can just about judge without getting into the rocket science end of it.