Don't worry about that message -- that's not an error -- from the output above, it looks like Bulbs is installed. Start up Rexster and and then try it out...
>>> from bulbs.rexster import Graph
>>> g = Graph()
>>> james = g.vertices.create(name="James")
>>> julie = g.vertices.create(name="Julie")
>>> g.edges.create(james, "knows", julie)