For what it's worth, I'm sure you didn't mean this to be sexist, since the phenomenon does exist in both directions. But your comment nonetheless reads unpleasantly, because the question "ever met a seriously hot girl?" assumes that the reader is a (straight) male, or, conceivably, a lesbian. That's the sort of wording that makes women feel unwelcome in communities like HN; it's essentially equivalent to having a discussion with a male and female colleague in which you address all of your comments to the man and ignore the woman. In general, you'll likely get a better response, and be able to avoid the "not sexist" disclaimers, if you write as if you were speaking to a mixed-gender audience (which you are!). In this case that could be as simple as s/girl/person/.