I have no real comparison as this is the first bag of pellets I have used. But I like them.Yeah, if that had been a really off brand I might not be surprised. B&B does good stuff; I think you should give them a pass for this one fluke happening.
Let us know how the pellets themselves do for you.
That looks like a piece of rubber belting.There could be a faulty bit of equipment at the plant and someone might recognise what the piece of rubber is.