Just wanted to add to those to "didn't have buttermilk on hand" - did you know you can make your own buttermilk? Check this out from food network: 4 1/2 teaspoons white vinegar, or fresh lemon juice, 1 cup milk
Place the vinegar in a glass-measuring cup, and add enough milk to make 1 cup total liquid. Stir to combine and let stand for 10 to 15 minutes (The mixture will begin to curdle).Use as needed or cover and refrigerate. I've done it - it's FRESH and GREAT!