Temps in the Huts

Every time I spend a night in one of the AMC huts during the shoulder season, I bring a heavy sleeping bag that I end up not wanting.

The website says that blankets are not provided in the self-service season, and that the rooms can get frigid, and that you should bring a season-appropriate bag plus maybe a sleeping bag liner.

But each of the times I've been, the rooms have been warm and there were blankets on every bed.

Packing right now for a night that could dip below 40F outside ... do I dare leave my warmer 3-season bag at home, and just bring a flimsy little summer sleeping bag?