I have been feeding laying pellets starting 11/2009, when the chickens started laying. These are layena pellets. They have been in my basement since 5/2009. They were meant for a batch of chickens (my second batch of 5) that would have been laying in 6/2009 but they were all killed by raccoons. Hence, I started anew with this 3rd batch of chickens, and this layena bag was only opened in 11/2009. My 4 chickens have almost finished with this 50 lb bag when I saw that there is this "caked stuff" at the bottom of the bucket feed. Picture as shown. What is that? Should I be concerned? The bag was stored in dry basement. No mice or rats in basement.