I was looking through some of the ingredients in the recall and I didn't find any that had rice protein or glutens, maybe I didn't look close enough...
I emailed Royal Canin about this exact question. I asked them to please clarify what ingredient triggered this latest recall.
Their response: (Most of the response was just a form-letter reply stating what their website already said). Then, this statement (looked pasted in - in a different font):
The reason for the extension of the recall is that those diets may have come into contact with the holding bins that the recalled diets had been in. It is just a precaution.
I find that a bit confusing / misleading, because they did say in the recall announcement that trace amounts of melamine WERE found in the food they recalled -- this statement implies a less serious situation.
They didn't really answer my question about suspect ingredients. It looks like the majority of the new foods on the list do have some form of rice. Maybe that's it? Just speculating -- who knows what it is.