I agree with Izzik--it was inappropriate, but the purpose was innocent; don't follow up to HQ unless a further problem develops, since the punishment from HQ could be very severe.

In fact, I think I'd reply to warn him off this behavior in the future. Something like:

Dear FA,

Thanks for your e-mail. I'm very flattered, but although you're attractive I'm afraid I'm already in a relationship(/you're just not my type/whatever).

Actually, it's probably a bad idea to e-mail passengers if you get their e-mail address from those surveys. I'm not going to report this to HQ, but there's a risk that if someone did--say, a homophobic straight person you mistook for gay--it could cause you severe problems.

BKKboy

--but then, that's me, and I tend to be both gentle and wordy.