I am the Kat that Walks By Itself

Has anyone else been getting these weird spammy comments on old posts on LJ? I've gotten three so far; the characteristic is that the comment is simply the repetition of one sentence from the actual post. Two of the comments I observed were exactly the same sentence on exactly the same post. I suspect it's a bot or a virus or something like that, because the accounts that did it looked like legitimate accounts, rather than accounts that had just been created for the purpose of spamming.

No, I can't point to the actual comments in question, because I deleted them. Weird comments are often used by spammers to test whether a site is being neglected, and therefore vulnerable to being used as a spam platform.