Honestly, Gaeta has done more with people he has known less... and who have done less for him. Even if ambrosia and hypervodka and whatever it is about this place that makes everything too simple weren't involved, he wouldn't count kissing Martha among his regrets.
"Wow is right." No, that about sums it up. He doesn't have anything cleverer to say, which is probably why he says what he does. "Thank you, Martha."