I've been watching this post for some time with great interest. I too have noticed my AM 500 is different, especially when hydrated, it seems to grow to a larger size than in the past. I didn't review the tags on my AM, so I don't know if the formula was tinkered with, but something is definitely different with my 500 at least. I have no clue if the differences are positive, negative, or benign - just saying I too notice a difference in the physical characteristics of my most recent 500 pellets.