So, I picked up a couple cans of Munton's Amber LME from the LHBS. When I opened the cans, they both had a thick, gooey kind of foam on top. Is this normal? I'd never used Munton's before, and don't recall anything like this with other extracts. I thought it might be from the canning/pastuerizing process, but I'm also not overly confident in the turnover of some of the products at the LHBS.