Changes to MEF in Silverlight 5?

Have there been any changes to the Managed Extensibility Framework in Silverlight 5?

Code that I have in Silverlight 4 has stopped working in Silverlight 5 - I now get an exception in CompositionInitializer.SatisfyImports() that a property exported in another assembly is not found.  The code works just fine in SL4.

Please advise.

Thanks,

Michael