Starter smells funny?

I harvested, washed and froze some WLP001 from a session Brown Ale several weeks ago. I pulled a vial from the freezer, thawed it and pitched it into a 750 ml starter (a ratio of 1:1 for gallons of water to lbs of DME). It took nearly 2 days to show activity but took off after that.

When I washed and froze the yeast, it was my first time and I was worried about having contaminated it in the process. Concerned, I have been smelling the starter during its fermentation. It smells very sweet and almost sour. Point being - I would NOT drink beer that smelled like that.

Does this sound like an infection? Is there a good way to know for sure? I don't want to ruin a 5 gallon batch if it is. Should I take it off the stir plate, letting the yeast fall out of suspension and taste some? Should I brew a gallon batch, pitching this starter and see how that turns out?

Thanks in advance, everyone!
-B

As a rule of thumb, if you have any doubts about your starter, don't use it. Better to get some fresh yeast than waste a batch of beer. As for the actual nature of the smell your experiencing, I've never encountered "sour" smelling yeast so I don't think that's normal. Usually, fresh yeast always smelled kinda vinous or wine like. And then my washed yeast smelled more like bakers yeast with a more neutral bready smell. Hope this helps you make your decision to keep or throw away the yeast.

Well, the sweetness I smell could almost be described as vinous. There are no visual signs of infection (no strange looking krausen). When I get home tonight I will taste some and see what I think then.