FWB drama!

Desi

I’ve been in a FWB relationship for about a month and a half now. We’d always been friends but never anything more. He asked me if I had sent anything (sexy pics, etc.) to anyone else since we started this “thing”. When I sad no, he said he was glad, because he didn’t like the thought of me sending those types of things to another guy. What does this mean? Is this a red flag?