If it is a gas inclusion bubble with smooth walls, nothing to worry. If the bubble walls are grainy, it may be different, but it is not a strength issue. I would advise to notify the importer, check the jug inner liner and just run it if the importer agrees with that. If the metal turns out to be porous at that spot, it will show up soon enough, and the importer will be the man to contact first. He will be in touch with the factory about the items he sells, and may set you up with a replacement.
A forum is a place to help each other. It does'nt do any good to vent engine flaws in public. A top brand will get hammered without having a chance to set things right first. Nobody will gain from that. Nobody.