One day I was picking up a package of Totino's Pizza Rolls (for the grandson) out of one of those big open deep freezes in our local store. I noticed the package had thawed, and when I checked out the others around it, they were also thawed. I found the manager and told him about it, and he said that the freezers were self-defrosting, and that just happened sometimes. He said it didn't hurt anything, that they were still good to buy. That in spite of the fact that it states clearly on the package not to re-freeze.
It's possible that your pork loins had been frozen, accidentally thawed, and then re-frozen. Or perhaps, somewhere in transport, the boxes weren't chilled properly, and some of the ones around the outside started to turn.
My daughter got terrible food poisoning from a chopped steak at a local restaurant once. We'd all had chopped steak, but her's apparently came from a different batch.