American with UK residency, do I need work permit?

I am an American citizen who has permanent residency in the UK. My husband, who is English, and I are currently living in Spain. While applying for jobs, several prospective employers asked whether I, as an American, would be required to get a work permit for Spain. I was under the impression that because I have legal residence in the UK and my husband is an EU citizen, that I would not need anything more than an NIE number to legally work here. Can anyone advise if this is the case? Many thanks, Minsgirl