Black Specks on Side of Starter Container
Hi, all. I've just gotten started keeping a sourdough starter over the past few months. However, over the past week or two, I've been noticing black specks appearing up on the side of the bowl in which I keep the starter, where starter has stuck when I stir it after feeding and dried. The black specks don't appear in the main bulk of the starter, just on the dried stuff on the side. I've transfered the starter to new bowls a few times now to clean out the container, but the spots keep coming back. The starter itself smells and tastes fine, and seems normally active; I haven't baked with it since the black specks appeared.
Some details about my procedures: I feed the starter 1 oz of tap water and 1 oz of organic white bread flour a day. The starter is kept out on a kitchen counter in a bowl with a piece of plastic wrap loosely over the top. I live in Ithaca, NY, and lately it's been rainy, with both cool and warm days; probably rainier than it has been so far when I've had the starter. (I also recently gave my sister down on Long Island some of the starter, and she's reporting the same specks.)
So, any idea what it might be? Can I just ignore it, or is it a source of contamination?