Wheel Wobble?

I got my new SP put together last night and put it on my tuning board, as it rolls one of my back wheels wobbles back and forth? When I free spin that same wheel as it slows down it wobbles to a stop. It is reversed with a spacer and just enough gap to spin freeley. Do I have a bad wheel or need to re-prep never had this happend before, Please Help! Thanks.
 
I have to agree with 5Kids, as I was prepping my SP cars tonight, I spun the wheels... and they wobbled slightly. I guess I just never paid a lot of attention to the wobble, because in my mind I knew the weight of the car would prevent any wobble a free spin would show.