I started drinking Horizon organic fat free milk and really like it but the last two cartons I've used, I found chunks leftover in the cartons after rinsing them out in the sink. They are white soft chunks, like slime balls. The milk still had a week before expiration and it smelled and tasted fine (I had already ate my bowl of cereal before rinsing the carton.) There were no chunks in my cereal, they were just in the carton. Anyone know what this is? I just contacted Horizon and haven't heard from them yet.