My cat seems to be sensitive to this. It is the one thing that is common among several dry foods I have given her. It seems to bring on skin rippling and/or diarrhea.
Someone I know from another forum has an epileptic dog, and one of his seizure triggers is rosemary extract. It took her a long time to narrow it down to that. I said this in the other thread, but since you mentioned the skin rippling I thought that was interesting. Feline hyperesthesia is thought by some vets/researchers to be a "partial seizure disorder", so maybe rosemary is a common seizure trigger.