I made a batch of BB RIS and its been in secondary for about a month and a half. I planned to bulk age it until July when I get back home. I came home for a couple of days, and checked it and there is a thin layer of foam on the top. Ive never seen this on any of my other beers. I know the info is vague, and I cant supply pictures, just curious if anyone can tell me if this is ok, or should I be concerned. Thanks.