I make buttermilk sourdough bread once a week, refreshing my starter the night before I bake. In between times, it sits in the fridge. Does it get sourer as it gets older? It smells a little stronger this week, not much, but stronger than before; it's very healthy, still bubbly.
If you look through the postings, not just the ones on the main page, you should find it. If not, you could go and sign in at www.kingarthurflour.com and the recipe is there under members' recipes.