gunk? does this happen when brewing? I have never seen a gunk. Only thing i have seen in vials is when it crystalizes. A friend of mine did the fridge trick. So once i heated it up. It dissolved back in.....

If the gears sterile. Heating it up will simply break the crystals down and melt it back in. Doesnt mean its not sterile... Refiltering wouldnt hurt though. but if its sterile already i see no sense in refiltering. it just crashed cuz the cold.