Originally Posted by The Showstopper
its possible. im positive Red Skull isnt dead, i think he was just transported to another realm. i dont think he would make it in Asgard without somebody noticing him. if he and Loki have met its probably safer to assume it was after Loki was transported away at the end of Thor
It's also entirely possible that the cube's power allowed Red Skull to be transported not only physically, but chronologically (that is, through time).