I see I slipped to "Senior Status". While I found in an inbox 16 months ago the membership renewal notice, I suspect I was sent another one a few months ago. But I probably deleted it without even noticing the subject because all notices from HF get filtered by me into a folder. I empty that folder often without scanning if there are many entries and I will go directly to Forums to read instead.
I don't have a recommendation to get around this, but do wonder if this has happened to others, too.