Absolutely magnificent oven spring on my two totally-commercial-yeast-free panned white loaves still in the oven!  I know "oven spring" can be overrated, but I never expected any and I've got it anyway.  Also my experiment with the buttermilk plant was successful and I have a good supply of buttermilk, though it's a little thin; I'm going to try some scones with it tonight.  I refreshed that with some reconstituted skim milk powder and it's sitting in the warmest place in the house, on top of the fridge.  I never would have tried the buttermilk plant if I hadn't got into sourdough, and it was the people here who inspired me, so a big thank you to TheFreshLoaf!