Hmm..now that I think about it..all they did was ask if it was the fans' idea.
But seeing that, it certainly does show that they were surprised and weren't expecting it at all.
I think it's more to do with the fact that it was American people going nuts over the pairing. Japan is far less bothered by homosexual relationships, unlike the West who still have great reservations over it for the most part. I personally believe that Clamp were surprised that the pairing seemed to have such support over in the west.
Besides, they didn't give away anything. I mean, if I were a mangaka I wouldn't just say whether or not a pairing was or wasn't going to happen. It'd ruin everything. Plus, in Japan the KuroFai following is MASSIVE. Clamp can't be obilivious to the pairing...if they are then they must be living under a rock. The pairing is definitely a favourite in Japan. Clamp didn't elude to whether or not it will or won't happen, but given the most recent chapters I can see that what's happening now both paralells Touya and Yuki's situation in CCS, and the situation Syaoran was in at the beginning of Tsubasa.
Clamp are sly little shy-devils. They're not afraid to hint at pairings, but they prefer to remain quiet about what will happen with the couple in question. Personally? I think they've been tossing little hints from the first time Kuro and Fai met. I wasn't a fan until book two or three, but I still noticed some faint hints when I was apathetic to the pairing.
Whether or not Clamp will do anything with the pairing is still unknown, but it's there. Clamp have laid the hints down, it's just up to them if they piece them all together (...which it seems like they're doing. In a not-so-subtle-but-still-subtle way. The latest developments can be taken in different ways...but...the main point is Kurogane and Fai can't ever be apart. Their relationship will be far more intense now, no matter what their relationship turns out to be. They're practically married XD...And that's an excellent thing in my opinion.)