The Skaven I got a few months ago (Rat Swarms, Clanrats, Rat Ogres, and Jezzails) was just fine too.
Edit: Actually I had a Rat Ogre bust off at the ankles, but I don't think that was a mold problem, just a hazard of the scale. I can't remember if it happened in the blister or when I was seperating hte ROs from the strip.