It's just excessive bacterial growth from being too old and in packaging. The film allows a certain amount of oxygen to pass through it, giving the product bloom (that's why you shouldn't freeze meat in its packaging - it allows freezer-burn to develop quickly). As the product ages, outside the wrap the meat dries and loses moisture. However, when inside the wrap, the moisture is retained and the moisture reacts with the meat, along with the acids, molds, and bacterias, etc. and produces the green tinge. Not uncommon sight; it only takes about Â½ a day too long past recommended for it to start appearing and esp. common when its higher humidity during cutting and packaging - had some storms lately? It's the evolvement from pink to grey to now green, one step away from stink and best not to eat it when it gets to that stage and can't be trimmed off.
More than once I've seen careless cutters do rewraps and chop up pork chops in the same condition and toss into the sausage lug; two days later they go to grind the sausage and the entire lug is spoiled and has to be tossed, the bacteria will spread like wildfire. (Worse yet I've seen them go ahead and make sausage from it - the next day all the sausage is green and has to be tossed, as well as getting some shoppers sick).
When on beef it's the same thing. If it's a cut where it can be trimmed off there's no damage, just throw away the affected trimming, just be sure to use the cut immediately as more will soon appear (as well as pork roasts, just trim it off - but on ribs, they're too thin).
Had one manager every Sat. morning would take all the pork and lamb trim, no matter what condition and was usually bad, and order us cutters to mix it in with the cheap ground beef on the early grind (6am grind) to get rid of it - man, that stuff was nasty (Saturdays there was no State Inspector who could take samples for adulterated ground meat). Don't know how many people got sick from that man. I refused once; I was taken in the cooler and dressed down verbally, screamed and yelled at, threatened to be written up for insubordination and fired and made to clean out the grease traps for the next several weeks every other night, plus the 1st cutter would leave the bone barrels out in the sun and heat for days until they were full of maggots about a foot deep, then make me scoop them out with my hands to clean them out (wouldn't let me dump them out on the drain, had to scoop them out and throw down the drain without hitting the floor). When you made union scale of over $17 hr and desparately needed your job you complied, but as soon as I became a manager an anonymous note went to his boss and eventually he got fired. The 1st cutter? I went from there to dep't manager in other stores, then to Deli/Bakery District Supervisor for 6 years, then took over the Meat District Supervisor's job when the previous one retired - the 1st cutter had made manager by then - I became his boss. His face turned whiter than his apron (or the maggots he'd made me scoop out) when I went into his meatroom and was introduced as his new boss by our VP of Meat Operations.
Sorry, waxed prolific there, got carried away - the stories I could tell....