Nipples lowk perpetually hard?

Hi, I had keyhole top surgery a year ago basically, results turned out great but there’s one aspect that’s kinda annoying. My nipples are usually pretty hard?? They don’t feel particularly tender or anything like that, they are just stiff and while other people probably don’t notice it, it makes me feel uncomfortable cuz I can see them through my shirt. Anyone else have this problem/ know a solution?