Registering a Little Guy TD in Washington

Has anybody in Washington registered a Little Guy from Oregon?
I'm selling my Little Guy and can provide the owner a bill of sale. Since Oregon does not require registering utility trailers under 1800 lbs, I never registered it in Oregon. The LG has a VIN stamp so I don't think it's the same process as registering a home built trailer.
The WA dept of licensing told the buyer he needs a Certificate of Origin and bill of sale. Does that sound right?
Thanks.
I'm selling my Little Guy and can provide the owner a bill of sale. Since Oregon does not require registering utility trailers under 1800 lbs, I never registered it in Oregon. The LG has a VIN stamp so I don't think it's the same process as registering a home built trailer.
The WA dept of licensing told the buyer he needs a Certificate of Origin and bill of sale. Does that sound right?
Thanks.