Polly-o Mozzerella Cheese

Question

I called the Mashgiach at the Polly-O company where they make the Polly-O Mozzerella Cheese. He told me all the ingredients that go into the cheese are either Chaf-K or O-U, but that Polly-O didn't want to spend more money on putting the O-U on the package for their Mozzerella cheeses. He is a conservative Rabbi, but he said he's very strict when it comes to Kashrut. Do you know anything about this?