"Snit" might not be a highly precise term, so one could argue for or against its applicability here. (@flozen could well have used a different second consonant in that word, which, while more inflammatory, might also have been appropriate.)
But let's look at the specific flow of the thread. In the first post, the OP says, in essence, "Please help me find something. I looked in X [IAFD] and it wasn't there." (Bonus points are awarded for use of the term "please.")
The first response said, "Take a look in Y (adultdvdempire), it might be in there."
The OP responds, "As I already said, I looked in X, and it wasn't there." This post adds nothing to the thread, as its contents had indeed been "already said." It does not say, but perhaps implies, that the OP looked in Y and didn't find the desired thing there. If that were the case, a better response would have been, "Thank you; I looked there, and and I didn't find it there either." Another approach would have been to not respond at all.
While it's not required that people use common courtesy in this forum, it doesn't hurt. In fact, it might even help: Courteous responses can encourage other Gentle Members to respond to requests for information, whilst non-courteous ones can discourage that.
I don't expect anyone else to jump in with an answer the original question of this thread.