I've updated my original post to include what was probably the single most important data point, which I'd forgotten.... that for the first time in the 2 1/2 years I've had the card I put 2 large purchases on it, representing about 67% of the credit limit. I'm guessing that that was the primary reason for the CLI.
Agreed. I received an auto CLI last year after two months of > 80% util. After that Chase couldn't wait to offer me more cards, so perhaps your luck with them will change as well.