Why do people mention "gay" and then ....?

I think that you did answer your own question, but there was nothing wrong with the question! It's important to make sure that people know where you stand on an issue so that they can respond appropriately. If you want to address a question to any group, whether it is a certain nationality, religion, or a group of homosexuals, you want to preface it with some kind of statement about why you are asking. Most people will be glad to answer questions about themselves or the groups that they belong to or represent if they feel that you are genuinely interested and are not being discriminatory. If someone were to ask me about my religion, I would be more inclined to answer honestly and politely to a sincere question rather than if they said "I think that Christians are fools, but why do you believe in _____? Am I making sense here?

I've found this with all sorts of things other then just "gay"... For instance, my extended family has started saying "black" and then have added, "not that there's anything wrong with that ..." ever since they've heard that my husband and I are adopting from Haiti. I think that people sometimes feel the need to add gay, black, Hindu ... (whatever) before describing someone who is different then them. I don't think that it always has to do with being Homophobic or Racist or any label you want to add to it.

I think in todays society that everyone is so afraid about being politically correct all the time that as soon as a 'discriminatory group' (for want of a better term) such as gay, asian, etc - needs to be mentioned, they feel they have to jump in and say something like 'not thats there anything wrong with that' or 'not that I have a problem' because they think it may be misinterpreted and then they would get a label, even though there is no other term to use realistically than gay.