Did it taste like yeast? In really hoppy beers when the hops drop out they can literally drop out. The one time I saw a bottle of Avery Maharaja in a local store, I picked it up and it looked like a snow globe. I think it was about 9 or 10 months old at that point. Needless to say, I did not purchase that bottle.
Not uncommon for unfiltered (and even some filtered) craft beers to flocculate after a long time. One of the few downsides of cans is you can’t see inside to know how gently to pour.
Not surprising to see that from a can that sat for a good stretch of time. Unless something changed recently Surly does not filter their beer, they do have a centrifuge now but that won’t get everything. I’ll get the same thing if I let a bottle/can of unfiltered beer sit cold for a long time and don’t pour very carefully,