Well both bunnies ate pellets from their new bag of SS with the same enthusiasm as normal. The bag was a 1.5kg one from Amazon. I expect that Amazon will have quite a high turnover of this product, so would think if it had changed, this bag would have contained any new recipe.
I presume this was the first time that your bunnies had been given the pellets ie the first time they have refused?
Has the problem continued today?