I have never made homemade vanilla before, so am not really sure what to expect. About 3 weeks ago I divided up 2 oz of Madagascar Bourbon vanilla beans in 1.5 L of Tower vodka in 4 bottles. Now, there's floating bits (like stringy particulates) and a yellowish-white film clinging to the sides of the bottle (on the top, above the liquid line). Is this normal? It doesn't really look like mold growing, but almost like little oily fat deposits. Thanks for any advice.