In the recent months I have been finding clumps in my store bought heavy cream. I have been buying various brands and have seen these clumps in all the samples. The cream is well within its expiration date and even when it's a little past I think it smells just fine. The clumps persist. This is not a problem I have encountered before but have seen it happen to ever sample of heavy cream I've bought since the summer. Though I know it's still "fine" it hits my ick-factor. I've tried shaking it, even straining it. What is happening?