When I used to admin a large website, the referral page was one of the ones that I flipped to as part of my usual rounds. It was just like looking at the "who's online" section of the forum to see which topics were getting the most readers. I did it multiple times a day, and multiple times a session. Once or twice a day would have been enough for that particular page, but it was just a twitch that I had to do all the relevant pages whether or not they'd be likely to pull up new info.

I don't think there's anything inherently wrong or weird or suspicious with them discovering the link that quickly. Well-run websites (like their physical-world equivalents) get better by paying attention to what other people are saying about them, whether it's on their own site or in other spaces.

But, I don't think it's smart of them, in any sense of the word, to have responded so quickly (or at all) here. Usually the most effective thing to do is to take into account what other people are saying in their own space, and then correct any misapprehensions or bugs or whatever in your own space. Which is why I say it might be rude for them to comment, but it's not suspicious.

For me, my focus is on the way that they respond, including where, when, and how they make the response, but not on the fact that they've found the criticism in the first place. Ditto when this came up about FanLib.