Argh! I just ran into the same problem! The model is drawn to 0.001" precision but there's no matching precision in layout. I can't simply convert to metric because Layout's mm precision is limited to 0.1mm. *sigh*
I wonder why precision got limited in Layout?
In general, Layout dimension precision options should at least match SketchUp's precision options.
I'm looking forward to having this fixed in the next version!