Lying about sex

My bf and I are going on three months now. We’ve talked about a certain sexual act a while back and he said he has never done it and never will. Today during a topic joking around, he said he has. I asked why he would like about something so small and he said because when we first met he didn’t wanna admit he has. He said he doesn’t see why I’m mad and it’s not lying.

I’m not upset about the act itself because we’re both adults with a past but why lie?! He’s making me seem crazy for being annoyed that he lied. I’m now questioning what other things has he lied about.

Do you believe I’m overreacting?