I started seeing these today....I heard some rumors that some of the old ringtones were DRM protected (???!?!), but haven't gotten confirmation. I'm guessing that there may be something in SC that may be causing the problem as most of those who are seeing the DRM messages appear to be on one SC variant or another.
I received them as well. I'm rooted with EB01. I noticed I get them after using USB storage on my laptop or turning on EasyTether. I don't have any music on my phone but I do use Zedge. I doubt those would have anything with DRM so not really sure.