Seems that Sanders is either making up ground very quickly or this poll is biased towards him.
Assuming this is still basically an internet-exclusive poll (irrespective of the refinements of the methodology), it likely favors Sanders to some degree. However, I tend to also believe that the PPP poll is favoring Clinton to a similar degree. Presidential primaries are largely nationalized affairs at this point and it makes absolutely no sense for Sanders to be receiving anywhere from 30-40% of the white vote nationally and in most states, but only 10-20% in SC (hopefully everyone will save the "but muh southern whites don't like Bernie" nonsense).