No, it is not deceptive.
We're only capable of revealing a certain portion of ourselves. A full sharing of who we are would require more bandwidth than is available through modes of human communication. The portions you choose to reveal should be those which have the most impact in the context of what you're trying to accomplish. If you feel your gender is of import on LessWrong, then you should take effort to make it more evident. Personally, I feel that ideas are far more important here, and gender should be [mostly] ignored.
If you aren't a meteorological event, I'm going to be disappointed.
So, my current username often reads as female. This is not intentional, and I am not female. Some on IRC have pointed out that this username could be considered misleading or deceptive. I have no real attachment to it, but I do have a few articles that I've been discussing and planning on posting here, and I think it would be confusing for others if I changed usernames, making it difficult for people to follow the genesis of certain ideas. However, I also don't want to mislead anybody.
Therefore, I pose the question to the community: is my current username deceptive or otherwise misleading, and should I change it?