At this point I cannot find evidence that it was Mueller's team that did so, but the FBI has seized one of the main servers of Russia's botnet which was used in 2016.
Which contains it at least once as a whole word match.
Re: false positives, it seems to treat "lie" and "lying" as synonyms, it just won't highlight the matched synonym in the result. But I can't imagine what it would be confusing FBI with if that's the case.
Lie / lying is a good example of weird spottiness, as they each return the same 4 posts in the Mueller thread;
The OP (May 6)
Two on page 3 (May 8)
And that same post of mine noted as a false positive, which uses it in a quote of a previous post inside a spoiler.