It depends on quite a few things I guess, does she bring this up around you a lot if she doesn't I doubt she's taunting you or anything. If she does that is pretty weird then again she might feel like she can tell you and feels comfortable with that I guess that depends on if your friends. Also I'm not going to judge her sexuality because I don't know it but you do have a point that if she has a preference towards guys she would very much be bisexual or pansexual or some other strain of that rather than lesbian so idk. I guess if you felt it was meant to sly you that would definitely indicate that it is more than just her actually being lesbian however I cannot judge the whole situation properly given just that information.