AR 4x tweeter question

[DKinYORKpa]

Someone was practicing on the 1804 Tannenberg organ at the museum where I work and he played something that really sounded good. It was Bach's Toccata & Fugue in D Minor. Since I had to ask him, you now know how familiar classic music is to me . That night I borrowed a CD from my step mom with Diane Bish playing it on the Muller organ. First I was blasting it through my 1960's Jensen 3-ways. Killer! This is what I'll use now to show off speakers. So then I throttled back the volume and switched over to my AR 4xs, with replaced period tweeters. When I raised the volume a bit, there was a horrible metallic clicking sound coming from the tweeter that I was closest to. I immediately turned down the volume and all was well. I've played the speakers since then but did not push them and they seem fine. So what did I hear? What's the diagnosis?