In a way it's unfortunate that OP had a passport handy, as it would be good to know what "second form of ID" would have been accepted, and what they would have done if you didn't have one. I'm not too concerned -- I have to assume a random credit card with name (but no photo) would be sufficient, and if you didn't have even that they might just flag for extra scrutiny. That's all I have with me for a domestic trip, as I suspect is the case for a very significant percentage of travelers, so it's really not possible that they'd deny passage in that case.

Sometime before May 3 next year I will start carrying my passport card also (got my last DL renewal during COVID so didn't go in to get it turned into RealID this cycle), but they really can't be requiring that until then.