I seem to remember that when I lost my mucus plug with my first pregnancy, it was more than a teaspoon! I have heard you can lose parts and regenrate it though. I would suggest calling your doctor tomorrow to ask if they would like you to come in to check, or if they feel it is a small enough quantity not to worry.
I had the same thing happen, and my OB says its normal. Basically, everyone produces mucus (nose, throat, bowels, etc). Its weird and unnerving when you're pregnant and have never had it happen. But there isn't anything wrong either.