In a reroute event part of the metadata sent over is step information which should be in its own json object. Right now however, it is being serialized as a string.
"step": "{distance=23, previousType=depart, upcomingType=turn, previousModifier=right, duration=14, upcomingModifier=left, distanceRemaining=23, previousName=West 21st Place, upcomingName=South Rockwell Street, durationRemaining=13, upcomingInstruction=Turn left onto South Rockwell Street, previousInstruction=Head east on West 21st Place}",