that's intresting... I would say that fermentation might not be done when you bottled but that usually caused overcarbonation or bottle bombs. Maybe its just because the yeast is getting stirred up and then the head lifts it up and makes it look like that. How long do you keep it in the fridge before you drink it? The longer you keep it cold the more compact the yeast cake and it wont get stirred up as easy, it will also be clearer beer.

Nice to see Cookeville brewers! I graduated from Tech in 2006.