It seems to be possible to get stuck between sudden death blocks and never die. It happened to an AI in the stage with the moving hardblocks (the ones with colored bulbs in the middle). Not sure if this is relevant or not but it happened between a sudden death block and the slot where the moving hardblock moves to (but seems to have nothing to do with the moving hardblock itself as it was inactive and an entire space away). The AI seemed be exactly between the 2 hardblocks rather than directly on the space.