Boyfriend wants me to stop wearing "revealing clothes"

My boyfriend and I were talking one night and he was saying something about being outside without a shirt on, and I said that I if I could go shirtless outside I would definitely try it. Then he got really uncomfortable and said he wouldn't like that. He then suddenly revealed to me that he feels incredibly uncomfortable and anxious when I wear revealing clothes out at all. I was really surprised by this because he's never said anything like this to me before, but he couldn't really explain why he felt this way which worried me. Is he becoming controlling? He said he couldn't make me do anything I don't want to do obviously, and he seemed to want to compromise but I'm just worried that this is a red flag! Especially because I really don't wear very revealing clothes at all, crop tops and shorts when it's hot out but that's pretty normal.