OK, so after 10 days in the primary, I opened up my bucket to find a very thin layer of something on the top of the beer. It kind of looked like an oil spill in the water.. Is this an infection, or simply something I shouldn't worry about? The only reason it caught my eye is because I've never seen anything like that before. When I put the auto-siphon in, it split it down the middle and then I took the pic. The circled section is what is visible in the picture of what I'm talking about:

