I spent most of the day today cleaning and relubing my Cannondale Synapse. I took the cassette off to clean the individual cogs and put it back on. I'm not sure if I screwed it up but now when I spin my pedals backwards the rear wheel would actually start spinning that way! Of course this only happens on the repair stand but still disturbing nonetheless. It doesn't happen nearly as much on my R700. The R700 has Shimano R550 (I think) wheels and the Synapse has Mavic Ksyriums. I'm a bit worried about the drag this might have on my rides.
Is this okay and if not what can I do to fix it?