I just recently got a D. pusilla in trade – maybe from the same guy – also no real roots, and just a few leaves. I've only had it maybe 2 weeks, and it seems to be doing well, has new growth, etc. I'll have to keep an eye on now though.
I do have a Platystele misera that's doing something similar though. Most of the new growth is short, like 1" tall. The old growth is still sticking around though, and it's been putting out some spikes, but they keep aborting.
So basically, I have no helpful information, but hope that somebody else does, since I'm having similar issues.