Matt,
It should be fine, my starters usually smell kind of sour too. With a stir plate you don't always get a krausen layer, but the color of wort changes to look lke light colored chocolate milk, kind of brown and thick from the yeast.
BTW, you don't want to leave it on a stir plate in warm temps for more then a couple days, yeast condition drops off. Depending on the yeast, I usually go a day on the stir plate, then cold crash & decant.
Regards,