Suspicious Activity on my Blog? Hmmm....

Listening to the Immortal Graun's Cleopatra e Cesare (Berlin 1742), while reading Privateering in Beverly (Massachusetts, during the Revolutionary War)--I opened my blog to record as much, and Lo! I discovered that my whole blog of these many years piddling-at had been removed, forever and forever, presumably "for Violation of Terms of Service...," but there at the end of that awful sentence was the somewhat hopeful notice that "Suspicious Activity" had been detected on my blog, and the slight encouragement that it might be time to change my password--So I did, and the whole blog came back intact. Gave me a nasty fright, though. What in the world is "Suspicious Activity"? I will now Google it, and see what it means.