Started a Brown Nut Ale 3 weeks ago. It's been in the secondary for 2 weeks. The odd thing is it started getting a layer of bubbles on the top of it a couple days ago and started bubbling again. Should I let it continue until it stops before I bottle it. I took a gravity reading this morning and it was 1.012 and a taste of it seems alright. Any help would be appreciated. Thanks in advance.