This happened a few nights ago... Me and my sister were talking about how someone we know just came out and my mom walks us to the bathroom and says "Don't surprise me with something like this when you're 20." Me and my sister gave each other a "wtf?" look and there was an awkward pause. The rest of the conversation went like this: Me: ".....ok?" Mom: *turns around for a second to look at me* "Just tell me now if you are." Me: ".....k" Mom: "You are?" Me: "......Yeah." Mom: "K." *shuts the bathroom door* She hasn't said anything about it since then... It happened so quickly I'm not sure if she thought I was joking or not. The way she asked makes me think she already knew but she's said things in the past that made me think she had no idea. It was a weird conversation anyway...
I'd really suggest you bringing it up again soon, whether or not you really want to talk about with her. So at least you can get rid of the "I think?" Say something like..."Mom, you do realize that I was serious when I told you that I was gay."
Or better yet "Hey, mom, thanks for being so cool with my being gay when I told you the other day." That way she can't freak out if she thought you were joking, because you just thanked her for being cool about it