That's what I say when somebody tells me something I didn't already know, but I can't think of anything else to respond with.
Actually maybe I should change that habit. Do you have any suggestions for what to do instead? It sometimes comes off as sarcastic, and other times I get the sort of respond you just gave. Neither outcome seems optimal.
"Oh, I didn't know that"
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?