My problem is that it appears as if the first stage is pushing the second into that rotation we saw. I could be wrong (I'm no expert) as my understanding of supersonic flow and its effects on bodies is minimal, but it seems intuitive to me that the second stage wouldn't rotate as it did if it was truly free after separation. Like I said above though, we'll find out!
I think you are right. The fact that the stages rotate in opposing manner at the same time strongly implies interaction of some sort (conservation of angular momentum anybody? ). Perhaps the SRB skirt retros need to be beefed up but that is going to be a tricky proposition given that the first stage is still burning during the sep process.