Yes, the size change is expected.
In our further attempts to deal with the anti-virus packages, we have disabled the compression when packing assemblies into the .xll file.
This means the assemblies in the resources are completely transparent and can more easily be inspected by the AV tools (perhaps).
A side effect is the larger add-in binaries.
I'm not sure yet whether we will keep the compression off for the next pre-release versions, or switch it back on.
Is the size much of an issue for you?
-Govert