I've had a White Labs vile of yeast in my fridge for a couple weeks and today when I went to start my brew, I noticed the yeast was seperated and kind of clumpy. I shook it up a little which helped but it still has a couple clumps in it. I gues they may go away with more agitation but I haven't seen this before and now I'm wondering if it's no good. Am I being too paranoid? Any thoughts?