Nope! Just leave him be! I had the same problem with DS, and his ped. said that once babies can roll over, parents can't just watch over them all night to make sure that they stay on their backs. Studies show that once they can roll over, most of the SIDS is limited anyway.
Of course, everything that I just mentioned should be talked about with your child's ped. or nurse just to make sure! (Gotta cover my bases!)
Hope that helps!
Welcome to the boards!
Hugs!