Stuff and I exchanged a PM regarding this . . . I've had the same problem a couple of times using DS on my WRX, by I haven't been able to pin down a cause. I mentioned it to DavidB a while back, and he suggested diluting DS with water to see if that helped. Unfortunately, I've been playing with so many spray waxes, spray sealants, boosters, QDs, etc., that I never got back to trying diluted DS.
Just as another data point, I've only noticed DS do this a couple of times, and I've used it quite a bit more than that. I haven't figured out if the streaking occurs due to weather conditions, or if it's the LSP that I'm using at the time reacting somehow with DS. I can't even recall now what LSP I had on the car the times I noticed the streaking.
Tort