Yes, I brought the STL file into SE saved it out, and then tried to save it as a PDF. That's when I get the error. In my experience, SE brings in STL files as faceted bodies, which are not good for much except viewing. This is mainly due to how STL files are structured for building RP parts. You can't really use them for assemblies or measuring or anything within SE. The best tool I have found for dealing with STL files is the Solid View program from Proto Labs.
[EDIT]: Meanwhile, excited by knowing about SolidView which can handle STL files as non-dumb models, I downloaded it but was disappointed to learn it did not support measuring in the trial version. The full version seems to support measurements which is quite thrilling.